The simplest thing might just be if the present foxhole were more slanted to a dual purpose of giving some cover to the tanks maybe enlarging it slightly or making it a bit taller.
I dont see a perfect solution is going to be possible since a real hull down might be dug out of a muddy hillside with shovels by individual soldiers. Thats just too custom
If foxholes were stackable like lego, that'd be awesome
It might be more an idea for map makers in that more skips, abandoned trucks, low and partly demolished walls could be left around city centers, these can give cover often.
People dont use whats there also, drivers should tell the gunner to pipe down a bit more often as a perfect shot often is the worst defensive position and you just cant have both that easily
Also bowl like formations can do the job, there isnt much of that available on most maps for whatever reason. I'll have to see if I can find example screenshots of 'natural' hull down cover
A Swedish tank -
