The tongue weight rating for a hitch does not take into account the lever arm effect of heavy bikes carried well behind the receiver. See this thread:
Thoughts on adding additional support to a bike rack to overcome the 120 lbs weight limit?
Also I have the option of using a RAV4, rated for towing, with my 1Up hitch rack. Just have to pay more for fuel.
Sure it is. Putting weight out for sure puts additional torsion on the hitch, but you have to understand that hitch ratings are not coming specifically from the hitch itself. First, it
The tongue weight rating for a hitch does not take into account the lever arm effect of heavy bikes carried well behind the receiver. See this thread:
Thoughts on adding additional support to a bike rack to overcome the 120 lbs weight limit?
Also I have the option of using a RAV4, rated for towing, with my 1Up hitch rack. Just have to pay more for fuel.
You are 100% correct, but also, as mentioned before, 1000s upon 1000's of folks have been towing their bikes and motorcycles on racks an hitches are not just braking off. The only time I have seen issues in when people try to mount bike racks on the back of travel trailers with very weak bumper welding and thin steel.
The tow rating has more to do with the rating for the suspension, brakes, vehicle dynamics, etc and then the tongue weight is 10% of max tow rating to preserve trailer sway dynamics. So 350lbs hitch is more coming from the 10% rule of the 3500 lb towing, not the pure rating of the hitch. For example, my Class 4 hitch on my Ford Expedition is rated 9k lbs towing and 900 lbs hitch weight. But, the same class IV hitch on the F150, can go up to 12k towing and 1,200 hitch weight. The hitch itself is the same and bolted to the frame. The ability of these 2 hitches to withstand the torsional bike forces are pretty much the same and the difference in rating is really tied back to the vehicle.
I know this does not answer what is the real max bike rack weight rating, but I wouldn't worry about it too much as long as you are using quality products and staying close to the weights specified on the hitch.