I am I a similar situation with my 2011 F250 CC LB gas. I searched the alarm program level and dealers either say it is not technically possible, or they just will not do it for liability reasons. No one at the Ford Super Duty Forums had a viable solution either. Although one poster says he put the sensors in a pressurized pvc capped pipe, other replies indicated that the sensors must rotate. Anyway, that was further than I was willing to go.
I am able to keep my tires at 58 psi without setting off the tpms, but no lower. It really irritates me that I cannot match my tire pressure to the load using the inflation tables because Ford requires the tires to be inflated for gvwr.