Advice for getting heavy boat atop SUV

Not sure
Not my system but the carpet runner I have is pretty heavy compared to the towels or Mexican rugs I tend to use to protect my vehicle. You can get it with a non-slip back that should help it stay put.

Aside from that, maybe try to point downwind.

what was wrong with the "just propping the bow at the back of your rack and then lifting and sliding the rest of the boat forward”. As mentioned you only have to lift half the boat at a time. You do it just like your were putting up a ladder on your house… I use that technique all the time for my 80lbs Pamlico 160, aka plastic kruger… if the rack does not end close enough to the rear of the vehicle they make a clear anti scuff tape that you can place on the roof… also for my plastic boats I don’t bother with saddles, sliders etc they just create more hassle.

Advice to get a long kayak on a SUV
Look at my posting a year ago on the Honda Element website of my 5’4" 120 lb wife loading our 20 ft Kaskazi tandem kayak on our Honda Element using a Rollerloader. I assist at the beginning and end of loading it on my TPS roof rack. The Rollerloader makes it a lot easier getting a long kayak on the tall Element but I use it loading kayaks on my much lower VW Jetta sportwagen.

Put it inside the vehicle
Don’t think anyone’s mentioned this, and I don’t know the lengths of the OP’s friend’s boat or vehicle, but a significant number of kayakers I paddled with recently in Florida simply slid their short SOT’s, SINK’s and SinPC’s into the beds of their pickups or right into the backs of their SUV’s.

One paddler even slid the boat into a PT Cruiser.