stand up paddle boards

My wife and I have been kicking around the idea of selling our tandem kayak to help finance a pair or SUPs.

Not that we don't have fun with the kayak, but it's awkward to transport and impractical if I want to go by myself while she's at work.

I've got both a tall Rola rack and a set of relentless fab bed bars that we use for the RTT. Ideally I'd like to also unload the tall Rola rack.....Can I get away with transporting a pair of 10' SUPs on bed bars, or do I need to keep the support farther apart?

 

I carry my Bic 10' sport SUP on the Thule xsporter, only supported about 4 ft apart average 70 mph for an hr each way. No issues at all.
I've also had an 11' on there, again no issues.