Here's an example of 6 boats on a Subaru. The bars are extra long, but if the boats are secured properly this is fine at highway speeds.
A trailer is much less than ideal for the poor road conditions that are regularly encountered getting to put-in and take-outs.
It's not unusual to have 6 kayaks on a roof rack for shuttle (from take-out to put-in). so at 40-45lbs each that's ~250lbs. In an extreme situation I've seen 10 kayaks tied on a roof rack, but I wouldn't want to do that for more than just the shuttle with that kind of load. I'm looking forward...
The answer I got from chatting with support is that the static weight limit is 700 lbs and the dynamic weight is 160 lbs. Not as much as I would have hoped. Loading up kayaks for shuttle would typically exceed 160 lbs
Pigeon River takeout at exit 447 on I-40, potentially partner with NOC or one of the other rafting companies.
Ocoee Whitewater Center on US 64
Chattooga Bull Sluice on US 76 at the SC, GA border.