I had a set of 35x12.5-17 fitted on rock warriors. I used My 1.5" Kit (linked above), a spydertrax 2" spacer for the wheels to get to an 18 offset. you need to also bend in the mud flag bracket. My truck already had the Body Mount chop from my earlier 34's and prior to the KDSS Max kit development.
it "could be needed" depending on offset but from customer feedback 35 and 25 offsets are both fine. Also I would shoot for an 11.5" width (285/295, etc) since the rear tire starts to become more of a problem tucking with the 12.5"s, I ended up using the timben active off road bump stops (also for my next phase of rear setup, which is TBA).
I am currently running the 34" setup for a reasonable Fuel range (heavy E rated 35's had me at about 9mpg). I have done a ton of miles on the 34" setup in the past year, but will be also going back to a 35" for off road (E rated Mud tire). With my 1.5" kit I am running Rock warriors with no spacers (stock offset for them), and a 285/75-17 Nitto ridge grappler tire. I do prefer not running a wheel spacer if possible.
So there are options for 35's. or 34"s depending on what you want to accomplish.