/diy/ - Do It Yourself

If I have to print a piece like this in this orientation instead of doing it flat or using the left/right side as the bottom (which is unavoidable for me here) is there anything I can do when slicing to get the highlighted flat bottom surface to be the same tolerance as its counterpart on the top? I don't need it to be as pretty as the top of course, I just need it to not sag down enough to affect tolerances after the supports are shaved off.