some time ago I was thinking that belts using beltlayer (was thinking the same about pipe from the AUP mod) would not go bellow but over structures
my way of thinking this was that:
- you use the G key to change between actual belt and a proxy item
- Proxy item would place proxy entity over classic structure and would place the belt on the beltlayer surface
- removing the proxy entity would remove the belt on beltlayer surface
- as proxy entity don't transport items on them, the belts would be covered
- we can set thoses procy as tall entities so we could still build under them the classical way

THe same logic could be used if belts don't go over, in that case we can display semi-transparent entities that would display only on alt mode