Lance,
I hear what your saying for sure, and for those of us that actually use or should I say abuse our rigs, weight in the wrong places can have catastrophic results at best.
In the back of my 4runner I have a pit box (tools, parts & fluids) and various things that I don't want out in the elements all strapped down no higher then the top of seats. Cooler is on floor behind driver seat, easy access for co-dog to get to.
Extras that need a home are:
My spare - currently in oem location underneath
Race truck spare? - on top or on a bumper
Fuel? - I hate how small the runners tank is plus I need to carry extra fuel for the race truck. I've carried it inside, but I usually end up sleepy with a cab smelling like fuel at best or a mess at worse.
Any suggestions?