Now I wouldn't know if this is possible but basically the mortar team kit would consist of two kits. One would be the actual mortar that can only be deployed with the direction and trajectory changed by the insurgent with that kit. The second part of the mortar team would be the insurgent that holds the shells and puts them into the mortar. That way 2 parts of the mortar team would have to stick together to get the mortar to work.
The guy with the shells would start with say 10 shells plus an ammo bag that refills 5 shells. The insurgent who holds the mortar also has an ammo bag that also refills 5 shells to the one who fires them. The mortar team would only have a basic defence say of a pistol (or whatever is appropriate) etc. The insurgent who fires the shells would hold the shells which are selectable as a weapon but can only use them on the mortar holder and then hits the fire button to drop them into the mortar.
I visage a three man (or more) squad that would be the mortar team . The two kit options that could either be found at the mosque or selectable via limited kits at the mosque and maybe a civilian collaborator who could use his binoculars for target finding. They could use a civilian car for getting around and to keep moving so troops cannot get get close enough to them. Don't ask me about range however, whatever is realistic I suppose
I know about the requestable mortar shelling already for insurgents so don't ask about that. This is purely as a limited kit. And a limited kit mortar team is not in the game.
