Some things like LDR leaf ambient, I know you can surpass and your map will run fine. (I think entdata is another). As you also said, you can use the propper tool to cut down on geometry, and where to use it? I'd imagine you could turn some of the badlands stage into model since it's all being rendered as world geometry (not even func_detail).
A friend of mine who made a bhop
map said he found combining the trigger entities also helped, yes.