We have a DR Field and Brush pull behind with a 20hp motor. It will cut anything it can bend over. We cut grass 6' tall no problem. Our terrain is hilly and rough to get to which is why we opted for the pull behind. Thing is a beast. 44" cut I believe. Got it half price a year used off a private seller.

the main issue with trying to use a LAWN mower riding more to cut food plots is, most cannot be raised high enough to cut without harming the food plot(like clover and such)
there decks are just not designed to handle higher cuts
next add in there designs on the mower itself, its NOT designed to have a slip like clutch for when you hit rocks and such, which you will find more often than not in most hunters food plots, again lower decks, don;t help here at all!

clover and such should be mowed at 6+ inches cutting height not lower, thus again, most lawn mowers don't cut that high, as most lawns are cut much shorter! and don't have random rocks sticking up all over! LOL

I've used a JD X729 with a 48 inch deck to mow an access road going into our hunting property a few times. Vegetation was 2 ft+ and I set the deck on the highest setting 5-6". It was a slow process and took multiple passes to clean up the 1/2 mile. Now I just hit it with the ATV sprayer twice a year.