I have 250 acres. Mostly wooded. Hilly. I'm guessing I have about 5 miles of roads, maybe less. Most of the roads are what we call 'jeep trails'. You can drive a truck on them, but just barely. No gravel or grading.
I have been able to maintain existing roads and cut some new ones, as well as clear 2-3 acres of planted pines with my Kubota
L4400 (45 hp, 4wd, R1s). I have a light duty 6' John Deere rotary cutter, a 6' Bushhog standard duty BB, 7 foot disk and FEL and have been able to do all this just with those things with the FEL, cutter and BB doing most of the work. For clearing, the FEL does most of the work. I cleared 2 acres of young pines, most of which where 4-6" in diameter but plenty at 8" and rarely some at 10". This was impossible in dry conditions, but when the ground is wet, I'd push the tree over flat and the roots would pop up. Then, hook the bucket lip under the roots and pop the tree out of the ground by curling, lifting and driving forward at the same time. Very effective. Same way on new roads/trails.
Having said all that, things that would have made the job much easier would be teeth on the bucket and most of all a grapple. Teeth are cheap....but I still don't have them yet. I think teeth are a great long term investment, a no brainer really....
The grapple is a different story. They are expensive, they require additional hydraulic plumbing and unless you need one continuously, you might find that after initial use it doesn't get used much.
That would be my case anyway. But, when clearing and moving brush it would be absolutely indespinsible. And moving large amounts of brush and trees without one can even be dangerous. You would have much more control of trunks and branches under tension with a grapple than a bucket. I made do with the bucket, but if I had it all to do again, I think I'd have tried to raise funds for the grapple. It would have made that big job easier, quicker and safer.
I was glad I had R1s for all of this. They held up fine in terms of puncture resistance and they provided the traction I needed to knock over trees which had to be done in wet muddy conditions and usually on a slope. They also provided good traction while shoving large piles (head high) of trunks and branches. R4s would provide stiffer sidewalls and better punture resistance, possibly at the expense of some traction depending on your specific conditions.
A medium duty rotary cutter would also be a plus. My light duty JD is built heavier than the KK and Howese type stuff but not as robust as a brand name medium duty. If you have the funds, get a medium duty, if not, you can get by with a basic cutter.
For heavy brush and woods work, prepare to bang up your tractor. I've got numerous scratches, a dent or two and had a stick punture my radiator (from down low on the side so no help from a grill guard) and in a similar case a branch came through and knocked off the fan belt; easy field fix there.