1. Spawn UAVs with this code (or similar) in an MP environment:
myUAV = [getPos player, 0, "B_UAV_02_F", WEST] call BIS_fnc_spawnVehicle;
createVehicleCrew (myUAV select 0);
2. Use diag_log to obtain the roles in the group taken by the UAV AI (usually the next available group).
3. Attempt to join that role and be forced to spectate players.