A simple suggestion I just was thinking of since I know AP mines have been nerfed fairly heavily now. Instead of you only getting 1 per person, allow say 2 AT miens or 3 AP mines to be carried in backback slots.
This would allow people who want to spend a bit more time building up a defence to lay a quick minefield. I wouldnt imagine it would be OP now with how AP mines in particular have been nerfed. Not to mention explosive packs can still clear out a lot of mines at once if they are placed near each other.
Could also do something similar to how guerrillas have that ability to carry extra TNT charges, maybe engineer squads could have the ability to carry more mines instead?