I have a ASV RC-30 with a bucket, root rake/Grapple, and Forks. And I have a tiny Mits MT372D Ag Tractor about 40" wide, I pull a 4' bushog with along with a box blades with scarifiers teeth- no loader.
That being said, I wouldn't and can't do clearing with the tractor, (nor moving dirt well)
I can't mow with the Tracked skidder either?
I can say the two machines are optimal for saving me hard physicals labor I would be stuck doing if I only had one of the two. It would be a choice of Chainsaws really.....
Having both, I am steadfast that even if my tractor had a FEL, it isn't efficient enough for me. I get to choose how much other stuff gets torn up trying to do a job, and that includes the wear on the machine.
Dont discount a RC-30 as plenty of machine to do the clearing, and can move mountains of dirt or debris. But having a nice tractor to mow, bushhog with, is a bonus.
I say this because I can see a 15k purchase of a low hour RC-30 and 5k in a small 3 cyl diesel tractor and bushog as being in just about anyone's reach- anyone who wants to clear their own 20 acres, and have the easiest time doing it.
Did i miss you say where you were and how clear you wanted it and how thick and mature the 20 acres is and needs to be? Picture are always good.
You DONT want wheels on your skidder, and a 40k tractor fel is still slow and inefficient, and not going to get the clearing done as simply as having the skidder.