35 Acres? If you try anything with a tractor you will be starting over again when you finally get done because they will be grown back by then. I would suggest a forestry mulcher like you talked about. I have run both the Fecon Drum Mulchers and also a Diamond Disc Mulcher on a John Deere 333G Skid Loader. Either one will work and once you get onto it you should be able to do 2 -3 Acres a day with one. Both will grind stumps just below surface a couple inches but not as deep as a designated stump grinder but for a pasture it should be just fine.