Sorry for the delay and I went back to the property and spent the weekend (no internet). I've only hauled the Viper (Pungo & Tarpon also) in the back of my pickup, so don't know the best car-topping recommendation. If using the front and rear tie downs, along with a center strap (or two) from side to side, I'd think it would be relatively secure. The fasteners don't appear to be super sturdy though. I did use the handle to pull the kayak partially onto shore with my wife aboard today (the water is chilly and didn't want to get her feet wet) and it seemed to be okay, but I tried not to put too much stress on it.
Viper kayaks website does have a contact form on their website and they may be able to provide the best recommendations.
Hardshell Kayak Sail Rigs
Full Size Sail Rig
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