Bed Bounce was an issue on my long bed when decelerating.
My solution was the addition of weight:
Line-X spray in bed
liner
Toyota thick rubber bed mat
LEER high top cap
Class III towing hitch
I also installed HD Bilstein shocks.
I run 50 PSI in my tires and get a little bounce from an empty
bed on rougher roads. This light bounce is eliminated when I
carry my normal 400 pounds of gear in the bed.
HTH ~