I have been towing our 34' 5er 11 years with our 2012 F350 SRW and it tows great. No problem on winding roads on mountain passes. Even in high cross winds it barely moves around. And I am within my weight ratings.
There are those who will be quick to tell you that you must have a DRW, no matter the size of the 5er, or you will be a danger to yourself and others on the road. Truth is is all comes down to weights. If the loaded pin weight of the 5er is well within the payload rating of the truck allowing for people and "stuff" you will have in your truck, you will be fine.