Do they move though? Sure, sure it reflects radar, sure it emits heat, great and fine. The solution is not all that difficult actually. JSTARS and Global Hawk operators look for the masses of ground units that are Moving as opposed to the ones that are stationary. That and make efficient use of HUMINTand ground reconaissance. Also, UAV operators would probably confirm the target in different electromagnetic bands, making sure that engine smoke is coming out of the right places, the heat is in the right places, and that none of it is too unrealistic (eg. the target stays hot while stationary for way past what its fuel is supposed to last )