As cool as it would be to have a mulcher come decimate that brush, you can certainly do a lot with what you have. Seeing the photo, I personally think you should throw your EA rotary cutter on and go see what you can do. By all means, back into it and don't drive over it first.
Do you have a hydraulic top link?
What "I" (remember, I'm just another random guy on the internet

) would do (or rather, have done many many times) is start backing into that brush really slowly, raise up the 3 point hitch so my cutter is off the ground, and then retract my hydraulic top link raising the rear of the cutter off the ground, fairly high (while keeping a close eye on the angle of the PTO shaft, you don't want it to steep) and slowly back into the pile, when I start hearing the brush getting chopped up by the blades, I start to extend the top link, lowering the rear of the cutter (but never lower than the front) and eventually start lowering the 3 point hitch so the cutter is back on the ground. Often I'll keep the 3point hitch down so the front of the cutter is about scraping the dirt, and keep the rear end a good foot or more off the ground. This helps bend the brush over and mulch it up.
It sounds like your pretty confident you will bend up your EA rotary cutter by backing into the brush. If that's the case, I suggest selling the cutter while it's in good shape, and buying the Brown 416 unit. The 416 is the newer version of the 472 that I have. It's quick hitch compatible. I 'believe' (but not certain) there may be a steel 'skirt' on the back of the 416 which is removable and replaceable with chains to open the back end up, on top of that, the back skirt is beefed up to 1/4" steel to take more of a beating in reverse. It doesn't really look that way in the photos on they're site, but some of the owners manual pics do appear that way, and I know the rear chains are optional. It would be very worthwhile to call Brown directly and ask them this, as well as their opinion on what they recommend. I have a feeling they would not suggest a tree cutter for this operation, and your tractor.
Regarding the Brown 416 vs. the EA rotary cutter, I looked quick at the specs and the Brown unit is certainly more heavy duty, by a substantial amount. Again, this is why I don't like their naming convention, they're "xtreme heavy duty" doesn't mean squat. The EA unit weighs a (respectable) 850lbs, and has 10 gauge (9/64") steel deck with a 75hp gear box. The Brown 416 weighs 1,100lbs and has a 7 gauge (3/16") steel deck with a 130hp gearbox. So yes, the Brown will be considerably more capable and hold up a lot better/longer than the EA unit.
(Note: I'm referring to Brown only because it's what I know, Bush Hog, Land Pride, and Woods etc. all have very heavy duty mowers as well, I'm not brand loyal)
A note about the Brown Tree Cutter: I wouldn't recommend this after seeing your pics. It seems you mostly have thick, heavy brush, vs. straight up trees. The rotary cutter is going to be better at mulching up all this material into pretty small pieces. The Tree Cutter, is more meant for just that, cutting the trees down, and of course it will mulch to some extent, but because of the open back design, it doesn't keep the material contained inside the cutter, but rather throws it out as soon as it's cut. The closed top design of the rotary cutters holds the material in longer and mulches it up to smaller pieces. This is why I like the 672 so much, it's the best of both worlds in that regard (super duty tough yet still a rotary cutter.) You could step up to Brown's Folding Deck design, but that is really way overkill for what your doing (and also typically used on 80+PTO hp.) I have only heard of one person using it behind a compact tractor, a John Deere 4720. He said it 'worked' but wasn't very ideal. I have some correspondence with him through email from some time back if your interested in details.
None of this will be as efficient and effective as a 100hp or more skidsteer with a mulching head on it, but it will be a lot cheaper, and you'll have your own equipment.
How many acres are like the photo you posted?
I can't stress enough, how important a grapple is to have. :thumbsup: