Well, there's no way I'm twirling my 75lb toon over my head...wish I were that young again... so:
The learning curve continues: I found that my 9' can be tied down safely to my 48" Thules.
Since I find it very awkward (and back spasm-ing) to try and lift the pontoon up sideways onto the rack, Here's my load up technique:
Pllace racks closer than the space between pontoons...For me approx 20"...then lean the toons against car pointing skyward, push the craft up onto roof...it slides up pretty easily but those recovering from hernia surgery may want to apply generous slathering of Vaseline to the roof of your vehicle. Toons now straddling the rack. Lift toon up onto rack on one side so it's now facing front to back, walk around and do same on other side. Tie down real good. The take down is the traditional slide the darn thing down the side of the vehicle. Remember to wipe off Vaseline or you may have a lot of explaining to do when you get home. (But, Honey, I told you I love my boat!" )
I know that 20" apart doesn't sound like enough space between rack bars, but the frame weight is centered and by using wide tie-down straps, I've had no problems. I zip around like it's not even there! And I love not attaching the toons at the put in.
Next problem to solve: I am starting a new thread re: trolling motor placement for those interested.