Indeed, the Town forum on EB is for minifig scale creations. Scale-wise, I'd say your creations fit in best with the Creator line, which is hosted in the Special Themes forum. Therefore, I'd say for most of your vehicles Special Themes should be the appropriate forum.
That's a shame, because we definitely don't want a to discourage a talented builder like you from posting your MOCs on EB. As you say, organising a LEGO forum isn't always straightforward and not every creation will 'naturally' fit in a particular forum.