The BetterF3 mod lets you customise pretty much everything about F3. In my setup, I've reduced it to a few lines that are all on the right side. This could complement MiniHUD very nicely (better FPS display, mob health, …), but there seems to be no way to display both at the same time. Even without this other mod, just with a small enough GUI size, displaying MiniHUD in one of the lower corners and the F3 screen at the same time would be no problem.