I have had 2 Keystone brands. A Springdale pull behind and a Copper Canyon Fifth wheel. The spring dale new would even come off the lot to start off with the brakes were not even hooked up at the factory. The cabinets doors would fall off. Traded this off for a bunk house 5er Copper canyon I had several issues with the overall quality. the final straw was the delamation of the side panels after 4 years with no factory standby of their products. Traded that in and lost my butt on a Forrest river 5er and you can for sure tell the difference in quality control.
The reason you see more is the keystone factory line is high speed high volume. I pretty sure they are one of the largest brnads now so the add on refrigs, heaters etc they get in bulk price so their rices are lower. Hope this explains my dislike for Keystone brands
On Towing with a fifth wheel or any trailer my suggestion is look at the trailer life tow charts or your truck mfg to get you capacities. I tow my fifth wheel with a 3/4 ton Ford with no issues just stay with in the capacities of you truck and you will be fine.