I would carry a spare for a 5th wheel, also a 20 ton bottle jack. Alfa's are heavy, if you have 2 axles and the tires are the G614 Goodyears, I would advise to go with the 215/75 R 17.5" wheels and tires. Since you have a 3 slide unit, I know that you are heavier than I am, and I am right at 16,400#. If you have 3 axles, then the G614's might be ok.
03 Silverado cclb 3500 drw, D/A, Reese 22k hitch
07 Alfa SeeYa Gold 30RL,2 slides,power everything