you can do a level kit and body lift for around $450 in parts plus labor. Will clear 35s and give enough room for the bounces off road. It will not give the ride of a $2000 suspension lift, but it will work. My current truck is the first I've done a suspension lift on. I've had three with body lifts. I am getting older and had back surgery and need all the help I can get off road anymore.
But seriously, no more than 18s if you plan on taking it anywhere. Hell, I'd have 15" wheels with my 35's if they'd clear the calipers. The more sidewall you can have the better you are in ANY off-road situation.
That's why I say you'll get laughed at by the off-road hardcore's. We all know the guys with the 20's and up are for show...