I've got a simple way to transport surfboards. I bought 4 tie-down extenders
and 2 rachet type tie-downs. I also made pads out of a couple old rolled up tee shirts and duct tape.
Loop the extenders around your main roll bar hoop and then again on your window bars. Place pads on window frame and main hoop. Place board/boards on pads then hook tie downs to extenders and sinch down.
This works topless or with a bikini top. I have tons of miles including a many Baja trip like this. I've had everything from a 5'10'' fish to 9'0'' comp longboards on my jeep without a problem.
"Shes under powered, has little axles, doesn't flex that well, but she'll get there!"