you can get a 33" tire no problem. the factory 275/55/20 is a 32" tire
if you look around eBay, you can get a front/rear kit that lifts anywhere from 1.5" to 3". They are essentially Leveling Kits that the 2004-2012 F-150 uses. The 3" kit should allow at least a 34" tire, and perhaps a 35" tire depending on how wide you run. The width is the killer part for fitment
I got my wife to okay letting me do a 2" lift on my Expy. I am upsizing to a 33" tire. Not looking for too much height
There is a guy here in the forums (Long EL) with a Black EL lifted 3" on 33/12.5/18" tires. looks really mean.
edit, here is Black EL's -
https://www.ford-trucks.com/forums/1...ml#post9600823