Lvmike: I have used and recommend the large garden size plastic bag and your favorite flea and tick spray liberally applied outside the vehicle and then tied shut before placing in the bed of my VarmintMobile.
The fleas that don't die quickly will probably not be gettin out of that situation!
Could you tie said bag to the roof of your 4Runner for about two more stands/set-ups before placing the bag and contents inside your rig?
Best of luck to ya.
Hold into the wind
VarmintGuy