I have a 2011 f150 xlt supercrew 2wd. Im looking to level it out and put some 33's or 35's on some 20 inch wheels. Seeking advice on what kit i should go with remember i tow my boat (21 lavey). Roughly 4-4500 pounds depending on how much gear and fuel i have in the boat. I'm looking to also do an air leveling kit with a compressor, tank, remote wireless controller and of course a train horn all to be mounted in the spare tire well. (truck sags pretty good when im hitched up, bottom of my trailer scrapes when coming or going into a parking lot with a steep entrance. looking for advice any help is appreciated. I'm not cheap i don't mind to spend money but i don't want to overspend for my needs. No i don't off road, truck only sees highway for the most part.

You'll probly find your answer on the Ford forums a bit quicker than here. Here's a good site for lift kits;

http://4wheelonline.com/liftkits.13