2015 keystone 311 impact with 2012 4x4 crew cab Durmax

I was at my dealer today and he had me hook up to my 36 ft impact and measure the truck tire to the top of the wheel well it was 10 1/4 inches, when he lowered the 2800 lb impact my truck doped 3 an 1/2 inches it looked level. he assured me when my Harley and gear was loader in the garage the hitch weight will be less. the cool part he told me I didn't need air bags. I'm now a proud owner of a 2015 keystone impact.