From my experience go BIG ......
I had a PUP for years and in 2006 I needed to replace my Explorer, so I jumped into a Dodge Dakota with 4.7L v8. In 2007 I purchased my Jayco 20BH and the Dakota struggled, so I purchased a 2007 Ram 1500. In 2009, I purchased my Eagle 256RKS. The Ram 1500 would pull it, but I didn't have enough payload and didn't like the stability, so I purchased a 2012 Ram 2500. What a difference, plenty of payload and 13,250 lb tow capacity. Tomorrow I trade in my 2009 256RKS Eagle for a 2015 Eagle 284BHBE. I know my Ram 2500 has plenty of payload and towing capacity for the new TT.
Moral of the story go, BIG in the beginning. You will not be sorry.
2012 Ram 2500 Crew Cab 4x4 5.7 Hemi 4.10
2015 Jayco Eagle 284BHBE
2009 Jayco Eagle Super Lite 256RKS
2007 Jayflight 20BH
1997 Fleetwood Cheyenne PUP
1984 Rockwood 1080 - PUP 1969 Coleman PUP