Share 'advice needed on how to mod cross bike for beg/int mtb trails'

i've ridden my cross bike on some not so technical moutain bike trails with ok success running mud 2s but they are pretty low volume and i have flatted a couple of times.  a few questions: 1)  i see a lot of 35mm clinchers but i know different manufacturers run big vs. small.  anyone have an opinion on what 'cross clincher tire has the highest volume and is very durable?  2)  could i run 29er mtb…