The problem appears to be that he'll have to back a 36-37" wide tractor with a 48" wide cutter 100 yards down multiple 60" rows between grape vine wires. That leaves 6" for margin of error on each side, looking backwards over his shoulders, through horrible stuff that is apparently 8' high in places.... piece of cake! :laughing:
Front mounted is the way to go.... watch this video of my little PT425 with a front mounted brush cutter taking out a large multiflora rose. . I can lift it 4' if needed, but rarely do. Its the most dangerous piece of equipment I own or have ever operated.
http://www.mossroad.com/PT425Videos/PT425MultiFloraRose.WMV
I'd think a small tracked skidsteer with a brush cutter would work well, but I don't know how narrow they are. I think the Bobcat T450 is under 60" wide, but that doesn't leave much margin for error.
Anyhow, good luck with your project. Sounds brutal. Got any pictures of the land?