I notice you live in CA. You'll do okay on flat roads but will suffer when climbing, which you'll probably surely do. All of my motor home experience has been on the west coast, and my first DP was a Cummins ISB with 660 torque towing a 4,400# toad. It really struggled to maintain 35 mph on a 5-6% mountain ascent. My current coach with a Cummins ISC with 1050 torque when I was towing the same toad would easily maintain ~45 mph on the same ascents.
I'm sure some folks will reply that as motor home owners we shouldn't be concerned about how fast we can go, and rather just sit back and enjoy the scenery. The problem is when you're severely holding up traffic and having to constantly use pull outs to let them by, it pretty much removes the enjoyment factor.
Bob, Sherron & Kinsey (Goldendoodle)
2017 Tiffin Phaeton 40QBH
2014 Jeep Cherokee Limited