I have used Bontrager XR 1.8 tyres on CXP33s with no rolling or anything else, so I would recommend ytou give your plan a go before worrying about new rims or wheels.
However, if you plan to use the lightweight singlespeed 29er lowpro for going off road then remember to leave mud clearance. Aluminium frames and fork crowns can get surprisingly damaged by gritty mud on too big tyres...
I have used Bontrager XR 1.8 tyres on CXP33s with no rolling or anything else, so I would recommend ytou give your plan a go before worrying about new rims or wheels.
However, if you plan to use the lightweight singlespeed 29er lowpro for going off road then remember to leave mud clearance. Aluminium frames and fork crowns can get surprisingly damaged by gritty mud on too big tyres...