newbie start from zero, nothing, nada !

APT wrote:

here is the rig: jay flight 248 RBS 27.5 feet long
Maximum weight fully loaded 7000lbs
tongue weight dry 555

pick up considered:
New silverado 1500 with the tow max package , 5.3 ltr, 3.42 axle,

That's a good combo. Get the HD towing package for the trans cooler. Tow rating is in the 9500 pound range. 3.42 axle is better than older 4-spds with 4.56, or plenty for RVing with 5 usable towing gears. RVers with the 2009+ GM 6-spd/3.42 say towing is comfortable in the 7k loaded range. The 2014's got lighter and more powerful so all the typical half tons RV limitations of payload shouldn't be a problem. Crew cab half tons mid trim level have 1700ish pounds.

I'm all for the weight police and towing a TT with a 3/4 ton would likely be more comfortable, but 7k loaded is perfectly in the half ton range of comfort while providing lower purchase and operating costs plus a better unloaded ride.