Dummy the trailer receptacle. I do not believe it alarms when you have a trailer hooked up, but I could be wrong. Or you could put the bikes in that big square thing behind the cab!

 

I've read some where now not find again to confirm when using the 4 pin trailer connector it will continue to work. when using the 7 pin connector it will disable the PAM (parking aid)
I drive a 2012 F250 XL and use a carrier Of course we are using the 4 pin. I would still like to disconnect permanently cause once in a blue moon will this truck not have something behind it