so i have a recruiting trip coming up, in which i will fly from boston to LA and back in the span of 28 hours. anyone have good ideas for solid, reasonably healthy snacks/meals i could bring along? doesn’t need to be low-carb, but if there are carbs i’d like to be able to know precisely how many there are.
A bag of almonds.
Large bag of your favorite nuts. I go to BJ’s and buy their 2 Lb bags of chopped walnuts and their 3 lb bags of almonds for trips. 1/4 cup of nuts gives you 6g carbs and 190 cals so you can make a meal out of 1/2 cup. It is easy to eat too many so I also bring along a soft rubber 1/4 cup which is useful in case I go to a buffet as well as for the nuts.
Another item is Swedish fish as each one brings my BG up exactly 10 points and a few bags do not take much space.
A lot of the airline food is often pretty healthy as well as long as you stay away from diabetic meals as the airline diabetic meals are loaded with carbs. Airlines like hospitals do not want you to go low on their watch hence they stuff you with carbs. There are usually always low carb fish and meat options on the plane, at least on United.
First Class, of course, has a lot more food options than coach.
On planes I bring seeds (I don’t bring nuts or peanuts personally just because I have life-threatening food allergies, and although I can eat nuts, I don’t want to trigger anyone else’s life-threatening allergy), coconut chips or other homemade low-carb chips, dark chocolate, homemade granola bars, veggies and dip (a small container of drip can be brought through security as a liquid), homemade muffins, and a meal or two such as chia pudding (without any liquid added) or a homemade sandwich, homemade low-carb pizza, or whatever else travels easily. I am always experimenting with new foods to see what’s easiest to travel with, since I travel a lot for work.
In the US, they have started checking all food brought through security. Instead of having them rifle through your bag, it makes things a lot easier if you put all your food in a clear container that you (or they) can just pull out. Also, if you have life-threatening food allergies like I do, you’re allowed to ask them to change their gloves so that they’re not cross-contaminating your food with previous foods they may have touched. (They do not open the food; they just take each type of item and swab the packaging.)
I actually pack food for my entire trip since I can’t eat out with my allergies. But when flying, I only bring snacks for the plain and an extra meal or two (one to eat while travelling, or two if needed, plus an extra in case of a delay). The rest of my food and preparation equipment I pack in my checked luggage.
Wow!!! I am amazed you would pack all of that for a 28 hr trip. Most of us find it much more convenient to just carry on for short trips. Since Boston to LA would be on a 2 class airplane, people that commute that route normally pay coach but fly first class with upgrades and status. First class always has good food options for diabetics (unless you have other issues such as allergies) and the US airlines look the other way when you board for first class with more than the standard allowable baggage cabin allowance.
I was just listing ideas for things I have brought in the past. I wouldn’t bring all of that in carry-on luggage unless I was travelling for a very long time. But I do always bring a meal or two or and an extra meal because plane food is 100% not an option and even airport food is challenging to find anything I can eat. I’ve been stranded in an airport and hotel for 24 hours due to delays unable to find anything I could eat and having run out of the food I’d brought (since it was the end of my trip). Totally sucks and probably not something people who don’t have multiple severe food allergies can understand. 
Luckily diabetes alone is much easier to deal with and you can just order or buy whatever you like and just eat around the parts you don’t want. My post was mostly to show that it’s really not an issue at all to fly with food as long as you read and follow the rules. I’ve gone on international trips of up to 12 days where I brought 100% of my own food other than fresh produce. No issues whatsoever with security or customs. Flying within a country is a cinch and at least in Canada you can bring whatever you want as carry-on as long as it’s not over 100 mL of liquid. (Though, as I said, I personally choose to avoid nuts as well as anything stinky like fish, or eggs if I could eat them.)
I just try to keep my replies close to what the op asks so that the thread does not start to meander into other territory or get hijacked by someone with an agenda. Personally, I eat low carb so for a 28 hr round trip it would be no issue to increase fat content in a couple of meals before trip and then can easily IF (Intermittent Fast) for the 28 hour trip and not worry about food, just stay on liquids. Could also cook 1/2 lb bacon, cut the strips in half, cool in fridge in a zip lock bag and then put bag in a FRIO pack for emergency snacks for such a short trip. We are all a little different and I have seen many a thread veer very quickly off topic when we start opining on issues the op neither asks the board, nor shows any interest in. On the other hand additional details can sometimes trigger a positive experience for the op that was not thought of during time of posting so it is a very fine line to tread.
The OP was asking about what snacks and meals they could bring along on a trip. So I thought my post was pretty on-topic? 
I guess it’s up to the OP what is relevant; if they feel their thread is getting too off-topic they can ask that people remain on-topic or bring in a moderator for help.
FRIOs only keep the things at around room temperature. They are only designed to protect from extreme heat, not provide any type of actual cooling. If I was bringing something that needed to be kept refrigerated (which I try to avoid in my carry-on luggage, but my checked luggage is full of refrigerated food) then I would bring it in a small insulated case with small ice packs.