I say use what you got. See if you can take off the locking mechanism that held the original seat on and see if you can attach it to your piece of plywood. Never done one before so don't go completely on what I say.
mainly will help in the spring/summer if I want to go fishing or something can throw a couple small tackle boxes in there. and other just odds and ends
__________________ Member #5 of the ME.com 5.0 Club
Current:
1985 Mustang GT Hatchback
Past:
1990 Mustang GT
1988 Mustang LX 5.0
by the time you get done adding stuff the bottom is gonna weigh more than the stock bottom heck it probably already does.
__________________ 2003 REDFIRE COBRA #3938 of 5082 @ 05/27/2003 1 of 414
MGW Shifter, Stingers, JLT, SS Inserts, MM FLSFC & CC Plates, SS Lines, H&R Race springs, IRS Brace, MRT Hood Struts ME.com Member #29 - 400rwhp/380rwtq