I dont like the idea of putting med crates on the kubel because it would force you to get a kubel if you went mechanized HQ. That said i agree sturmpios need to have some of their utility dispersed.
Something that I/others have tossed around previously is giving volksgrenadiers a minesweeper package that uses up all weapon slots. The squad may or may not unlock repairs but if it does they would be slow repairs like conscript or pgren repairs(1hp per second per model).
Its a lesser evil. Kubel is cheap, have very powerfull vet1 ability and in general can be quite usefull as a support unit and easily replaсable. On the other hand keeping meds on STs meaning that if you go for Mech and lose them along the major part of the game, you would have to spend 300MP which is huge at any point of the game.
My point is, its better to make a small change like this to healing, instead of trying to think whole another way of tech\upgrade healing system.
Speaking of sweeping, I honestly dont like the idea of sweeping volks. Because they are still way too expensive and weak un-upgraded to become sweeping unit imo.
STs sweeping is alright somehow, because at least your combat capability is un-effected. With volks you will be paying 260 MP, for an slightly better engineer squad, which still will be brutalised by anything but other engis units.