My spouse and I are looking at purchasing our first RV, he grew up camping, I did not.... We have a 2019 Chevy Silverado 6.2L with max trailering, manufacturers tow rating of 12,200 pounds and are ...
Buy used...have had several friends who bought new upscale RVs...they all had multiple issues from new...and guess what, warranty work typically comes after work from paying customers is complete. Warranties typically don't have maximum time frames for repair.
Another vote for...you probably can't safely tow 12k lbs if you look at all the numbers.