Much of the restrictions in where and how a sensor is applied are just to make it kind of "idiot-proof".
In fact, you can put the sensor anywhere you can get the wire subcutaneous, and the fat layer necessary is really very thin if you are careful and precise during insertion to insure the wire goes in right (not too steep going through the fat layer, too shallow going into the subdural part of the skin and not getting proper contact interstitial fluids).
With practice, you can get quite skilled at applying one-handed in the tricep area. Main thing to look for is the sensor carrier being nice and flat relative to the skin, not tipped forward/back or to the side AT ALL.