AFR is in the 9Z's. I'll try to explain both Trace Rate and AFR this way. Travel Adjust w/JR or ATV w/Futaba adjusts the throw of each individual channel. Trace Rate w/JR and AFR w/Futaba adjusts the throw of the stick. Example; you are using two channels on the ailerons. You use Travel Adjust to get each aileron throwing equally and you use Trace Rate to change the amount of roll throw you want.

With a JR the DR maxes out at 100%, but the Trace rate can go to 150%. I'm not familiar with the Futaba 9C, but I'll bet the DR will go to 140%. Just keep increasing it until you find the point where the servo quits moving before the stick is at max. Back the throw down just a bit from that point. Then adjust the mechanical linkage to give you the control surface throw you want.

I would not live with any mushiness regardless of the fuel levels. It's an indication that the loads are too high on the servo. Either get the linkage set-up correct or overkill it with a bigger servo. But whatever you do make sure the linkage set-up is correct.

Putting in a lot of elevator throw is not the answer, either. This just makes this leverage issue worse. Please check my BobCat set-up article on BVM's website for a good elevator set-up. I used 20 degrees of up and 24 of down. My BC would snap fine with this amount.