I had a 31' Class C that I carried 2 sea kayaks on. I carried these all over the east coast from Florida to Maine to Wisconsin, to Tennessee.
The same method could work with a Class A.
I basically made a set of stryofoam holders that cradled each of the kayaks up off the top of the Class C's roof. Here are the steps.
- I bought a sheet of thinner Styrofoam, made the shape that I wanted and then filled them with the can foam. I embedded a piece of rope into each so that they would be held on/under the kayak to make it easier to hold everything in place. I made the blocks high enough to carry the kayaks up side down to keep water out.
- The tips of the kayaks had to be separated to go on either side of the AC unit so I used a piece of PVC pipe (~+2' long) & threaded a rope through it with eyes on either side, the rope from the Styrofoam blocks would then be threaded through the eyes as I tied everything down. Did the same thing in the back, this kept the kayaks evenly spaced and prevented movement. In the middle of the PVC pipe I cut an opening an pulled the rope out and made a eye This would be used to string a rope across the top of the Kayaks and down both sides of the RV.
- To hold the front down I took some metal channel and fastened it to the frame in front of the back tire, having enough exposed to put an eye bolt on either side. I used some quick carbineer type clips to make it faster to connect.
- I used a couple of small foam blocks you buy to put a canoe on a car roof, I used these to hold the rope of the top corners of the RV.
- To hold down the back of the kayaks I dropped a rope from each kayak and tied to my trailer hitch/bike rake.
- To load the kayaks I would put the foam blocks in place on the roof, prop up a kayak against the back, go on top, pull the kayak up and put them into their place, I'd then just tie everything down.
Overall everything worked good. Never took any pictures of the setup although a lot of people stopped me and asked how I did it.
You might consider using strapping to hold the kayaks down as the rope had a tendency to stretch. I used this set up for ~10 years taking the kayaks from TN to FL, Wisconsin, Maine, and all places along the east coast.