Transporting paddleboards?

This looks a lot like the one next to us at a campground last week. Maybe not the same brand, but it allows carrying two kayaks and two bikes off the trailer hitch receiver. That upper cross beam is hinged at the passenger side, so one end of the kayak (don't see why it couldn't be a board) tips into a pocket at the bottom of the rack (near the dog). Then it's a one person job to stand the craft on end and secure with a couple cables and straps. Then close the beam. There are aluminum channels to hold the bikes' wheels then they strap in place too.

I built my own exactly like the one in the above picture. Made it for 300 in materials far from the grand plus for the one above. vertical bike carriers are awesome and paddle boards on both sides is the way to go. Forget trying to use the roof won't work effectively. Keep in mind heights I'm just below the ac unit so it's OK. I primarily kiteboard so adding surfboards is easy with the rack. Best mod ever. I have a paddle board cover highly recommend and full lock system to keep it secure and safe from road debris and crackheads. fiberglass is fragile and the naked racks are for pavement people only. I boondock and kite in pretty remote places that have a lot of dirt roads.

The one thing I didn't like on the kayackrack.com one was tail clearance. one dip or uphill and it will touch down I put mine up just below the rear bumper and have no problems again watch your clearance if you make your own and I also made mine to keep the tailights clear at all times for legal purposes

Either this or get a blow up board I prefer fiberglass my self with g10 glass fins over blowups

I know this isn't exactly what you asked, but just throwing out the idea of inflatables. We love our Tower inflatable SUPs, we also have one of another brand, but I don't like it as well as our Tower brand ones. Easy to transport and easy to store.

I'm on about my 8th RV and I always keep surfboards on the roof. I recently added paddleboards to my surf activities (I love SUP!), and plan to keep at least 3 on the roof of my new-to-me 1989 Jamee Class C. Mine has a ladder though. Is there any reason you don't want to just add a ladder? Do you suspect that your roof can't handle the weight?

For mine, I plan to add a bunch of cargo boxes and will be storing at least 1 whitewater kayak, probably a surfski too, and 3 sups. I'm going to remove the AC to give me more room.