To all you 29er's out there!

Quick question,
I'm converting my tricross from SSCX to a kind of lightweight singlespeed 29er lowpro (V-brakes, fatter tyres, wide flat bars).

What max size tyre would you recommend on an open pro rim? I'd like to think that I can go up to 2" but maybe it means too much side roll.

Will a tricross take 2" ?

That's what I'd wonder.

Do you reckon there's a clever way to sort out the brake reach for a 650B conversion? It would involve a new wheelset, but you'd want wider rims anyway.