j bars and cargo box

Does anyone drive around with 2 kayaks in J bars and a cargo box like the rocket box on their vehicle? The reason I ask is that I need to transport 2 kayaks across the country and have room in the truck bed to sleep. The bed cap has Yakima towers and 58" bars. I'm curious as to what geometries work to carry two kayaks and cargo box. A trailer is not out of the question, but I would have a couple issues with registering one in two states versus just carrying on top.

Do the Yakima towers on the canopy have a track or are they mounted with any kind of distributing backing plate?  What do you think is your total static load?
 
I'd be reluctant to do that configuration on my Tacoma.  I'd opt to borrow a trailer for the trip, or buy and resell a trailer for said purpose.

Not sure two j bars would fit with a box. I fit one hullavator and a cargo box with room to spare on the same bars. I think weight is really your problem though. Unless you have extra support somewhere two fishing yaks probably take up most of your capacity. I think it's 160 lbs on the crossbars when mounted on a car. A shell is weaker than the mounts on my forester.

Plus 1 for trailer.

A trailer is probably the safest option, and I'd be able to get WAY more cargo down the road. I could probably mount the kayaks to the top of a U-haul.

Back to the original question. My cap has tracks for the towers. The total load would likely be under 200 pounds with cargo box loaded. The online gurus say 165 pounds for each bar so 200 total is well within limits. The two kayaks are less than 100 total. I'm also seeing a lot of people saying they carry 4 kayaks at a time on top of Subarus, so I think it would be safe except for maybe crash loads.

yakbass, how much bar is left with one j bar and cargo box installed? I have thought about upgrading to 66" bars in the past.

I haven't measured but I bet you could get both up there it would be snug though. Depends on the boat and box. Can your camper shell support the weight is more the issue than the bars themselves.

Yakima has "how much crap will fit on my bar" chart. If you look for cross bars on Amazon you'll probably find the pic in one of the results. I was just looking at it earlier today, in the midst of my own Yakima crisis.

I have strapped together and stacked the kayaks on top of each other before. Don't use any saddles and strap directly to the bars. It depends on the kind of kayak weather you put one up and one down or nest them. Place a couple of strategically placed noodles for padding between them if you want. As mentioned, this is all considering the bars have the capacity for the load, and defiantly use bow and stern tie-downs and you should be fine.

Find the rating on your bed cover and we can give you a definite answer.

Look into a lumber rack. They are designed to carry real weight and distribute it directly to the chassis of your truck. They make models that work with bed caps, especially if the cap is a bit older style and doesn't have the hangover covering the edge of the truck bed rails. Call around to some places local to you that sell truck caps and accessories and see what they have that will work. Far superior to Yakima/Thule style bars.

I have an ARE cap already installed so getting another rack is not the best option for me. The best I could find for a load cap number is a third of 550lbs which puts it a little under 200. However that is acceptable for me as published load cap numbers are typically a third or quarter of the maximum, and 200 was a high guess.

In case you were wondering why I am traveling across country with 2 kayaks, I am currently on a temporary assignment on the East coast and plan to build a wooden kayak in a couple week while I am here. I drove one kayak out here when I started work. My assignment is supposed to run out at the end of July so my plan is to camp/kayak fish across Canada for my return trip. Check 2 things off the ol' bucket list (build wooden kayak, fish freshwater in Canada).

Well first off that's badass. If you are at the limit you should be fine. I have overloaded mine on several hour freeway trips. My racks did show some good droop. It helps that your boats are light. Most of us couldn't get away with that as the our boats are mostly 65+ lbs.