To this end, I got a pair of second hand suspension forks that reputedly had the best clearance for 29x3 inch tyres of flea bay in order to fit them to my krampus, see how it goes (trying new things is good).
Fun to ride something different, a little more comfort (particularly for my dodgy right hand), fun to ride, perhaps felt a little faster on the properly rough stuff. Minor niggles are increased weight and not much mud clearance so once the chronicles picked a bit of dirt up you could then hear little stones pinging off the brace, no big deal I guess.

Then, I decided that a smaller tyre at about a 2.75 like the 27.5+ wtb ones might work well. Save a bit of weight, keep some of the 29+ ride and have extra clearance. A small amount of research showed that panaracers fat B nimble were supposedly smaller. So, I bought some and fitted them to a set of wheels built with blunt 35's and smaller they are...

just look at all that clearance! Lighter too at 750g so not bad all.

they measure up as follows:
Dually 45mm + Chronicle = 74mm / 76mm casing / tread
Blunt 35mm + FatB Nim = 67.5mm casing (tread is a sniff narrower)
Anyway, thought I'd share in case it was of any use.
How it rides remains to be seen later on today.