Hi - Okay have been in a very similar situation in the past. In 2010 we bought two Hobie outbacks roughly 90 pounds per. We put them on the roof for one trip and after the trip I said "nope". Not only were they impossible to get up there, I had zero faith that this was a good way to haul them. They wobbled all over the place and I was like "great, going to fling two state of the art kayaks on to I-90 at 75 mph."
Since 2010 we have upgraded twice, first Outbacks again in 2015 and then just last year we went to a 2021 Pro Angler 360 and a 2021 Outback.
Alright so now you have some context. Bottom line, we have two heavy kayaks, and have had two heavy kayaks for a long time. In terms of vehicles we have a Jeep and an Explorer, so no beds, ultimately we needed a trailer solution.
What we did is bought a Triton 8 Foot ATV trailer. Now, you can place the kayaks on the trailer as is and make it work - but it's surprisingly more difficult than you would think, simply because properly tying down and anchoring a kayak to an ATV trailer is well, just kind of weird.
The answer is buying a stake pocket kit and making a custom solution. Basically once you install the stake pocket kit on the trailer, the world is your oyster and you design with treated 2x4's to your hearts content. Our trailer is now beautifully outfitted with a modular and removable "jig" that fits both our kayaks perfectly. I also added two overhead rails that hold fishing rods most of the time but also can be used to mount a third kayak (which we have done).
Now, come winter when you are done with the rack, you remove it and store in the garage and you have a nice flat ATV trailer to use all winter. I absolutely love my trailer and I would love to make a business out of building them for people, problem is I just don't think there is a market for custom made double kayak trailer solutions! Its just kind of something you build for yourself if the need arises. If interested in going this route let me know and I can send pics, give further advice etc.