There is always the Thule goal post. Puts a damper on towing though. Then I thought about modifying it to sit on the bumper. More $. Then I priced the roof rack. Even more $. You need to support the yak where it needs support. It is not about the length of over hang. I rest mine at the bulkhead on the stern and the bow falls near the opening on the cockpit. I find it gives ample support without distortion.
The foam blocks I bought especially made for resting a boat on. Picked them up at an outfitters store. They had the groove cut in them for a square bar already. I just made some relief cuts to fit them to my rack.
Went well until she saw me still on the shore then she jumped off and swam to shore. Then she swam out to me and tried to get in my kayak! That was almost a roll over!