-make fueltruck driveable
as you see it is a static, it is modelled as a static and would need much work to be made driveable. there is a hose etc from it, static. + new players will expect it to have fuelling abilities. so no, sorry.
-give ammotruck increased blastdamage when destroyed
also no, players will abuse it and make suicide bombing runs with it. even I would do that, it would be used as a weapon, not a support as intended. Result will be the guns that do need its ammo, will not get it. because players will charge enemy positions and blow themselves up with it.