Daryl,
First, some thoughts about types of grasses and mowers. I have tall fescue grass; it's delicate, tall, and is easily mashed down. For grass like this, a zero turn mower is best as the grass gets cut before the wheels can mash it down. My
BX2200 does a pretty good job in that the front wheels do mash the grass down some, but the mid-mount mower deck cuts the grass before the heavier rear wheels touch it. If I had a rear 3-point hitch finish mower, the cutting deck would follow the heavy rear wheels and much of the grass would still be lying down when the deck crossed it, thus tall grass would soon spring back up, uncut.
You are in Florida. I grew up in south Georgia and I'm guessing you have the same grass I cut as a kid. Now I haven't lived there in 26 years so I apologize if some part of my memory fails me. If I remember correctly, you probably have Bermuda and Centipede grasses. Again, if memory serves me correctly, these grasses are "runner" type grasses, with a ground hugging running vine and blades that don't rise too awfully high-also blades that are tough & resilient and pop right back up after being mashed down. I'm thinking such grasses could be cut pretty well with a 3ph rear finish mower, eliminating your need for a proprietary MMM (mid-mount mower).
I think a small older tractor with a standard rear PTO, but no mid-PTO could serve you well. You can get rear rough cutters (brush hogs) as small as 36" up to, well, way bigger than you'd need; this could easily cut your rough stuff. My 42" GearMore rough cutter handles 6 ft. high dense material easily. A rear finish mower for your lawn could mount on the 3ph too, as well as all kinds of other attachments. I've seen old B series Kubotas as small as my BX and older Ford models even smaller than my BX. They have std. PTO & Cat. 1 3ph. If you have a flat concrete surface you can build wheeled dollies easily & cheaply to wheel these implements right up to the 3ph. (And with a small tractor & small implements, it's even easier.)
I have a DR line trimmer on bicycle wheels and a self-propelled Troy siclebar cutter. Stay away from that Dr. rough cutter. With the non self-propelled machines, you have to fight inertia and gravity. With the self-propelled ones, you have to fight the machine itself. Those handlebar controls are awful. It's like trying to hitch a plow to an alligator and make the thing go where you want it to as opposed to sitting on top of and having total control over, well, a REAL TRACTOR. The DR. costs way more than a 3ph rough cutter ($700 vs $3500) and the Dr. does only 1 function and you'll exhaust yourself walking behind it having to drive it (and I mean DRIVE in the very ACTIVE sense like it used to mean whipping and pushing uncooperative mules or oxen to go where you want them to go).
Well, that's my 2 cents worth (might be worth even less), but hope they're some thoughts that might help.
Good luck,
Tom