Isn't it fun to spend someone elses money!
If we were talking unlimited budget, I'd say get yourself a 50 to 75 HP tractor, a tiller, a disc, a chisel plow, and all the rest of the goodies that've come up so far. But I don't recall hearing the "unlimited budget" decree.
So, Back to the original question. A 20 to 25 HP tractor will handle a 6' disc in UNPLOWED ground. It won't dig in far enough to bog you down. In plowed ground, you're gonna have a handfull. I'd stay with 4 to 5'. 3-point disc's aren't known for their deep penetration. That's primarily because they tend to be lighter weight. (Although there are some HEAVYweight 3-pointers around)
I'd forget any notion of using a chisel plow with anything smaller than 50 HP. (And then, you'd still need to stay relatively small) For no more ground that you're talking, a simple single-shank subsoiler would do the trick if you truely do need to rip open the soil. There's a difference between "being able to pull a given implement" and "pulling it on a sustained basis without trashing your tractor". Once again, you aren't talking hundreds of acres here.
One thing to remember. With a deer plot, you aren't after the maximum yields like a grain farmer would be. You don't need to do everything to optimum levels. Just getting a good, solid stand with your crop is enough.
If it were me, and I was starting off with a clean slate, I'd consider something like a Kasco Eco-drill (Kasco Mfg. Shelbyville, Indiana) (no-till planter) and a sprayer. Hit the areas with round-up. Then come back a few days later and no-till your "crop". Less wear and tear on the equipment, and you'll get every bit as good of a crop.