You mention the states you will be in but not the type of stay; structured camp ground you pay for, National Forest and State structured camp grounds, boon-docking, or being in CO rough boon-docking (remote FR and jeep trails).
If traveling and staying in structured camp grounds you can get into the lites and ultra-lites in the 20' +, if boon-docking you need tougher construction than lites but they get heavy so 18' or less.
Regardless of your choice stay within the weights that the others are discussing.
Happy trailering.