I like that "inner tube" idead over the fender well that the OP mentioned. In the past, I'd shovel lots of salted sand into the bed over the liner and that would get me around plowing driveways all winter. With the truck rusted out from undr me the only area not affected is where I loaded that road mixture. If I got stuck I got out and shoveled some under the wheels.
2010 Cedar Creek 5th Wheel 34SATS "The Beast"
2006 Ford F350 Lariat 6.0L Diesel
2003 Harley Heritage Softail "Hogzilla"
1988 Harley Softail Custom "The Fireman"
1986 Marriage to "Wifey" (patience of a saint)