design one and build it, would be the best way in my opinion.
ie one that sits mainly low down, and goes over the entire width, so it wont move around (although depending on the design it shouldnt really move with the weight of tools)
basically it would be secured without creating any holes in the flooring etc.
draws may not be a good idea depdning on how it is mounted because a fast corner could open them up and send stuff going everywhere
but you should also take into account the access to the spare wheel.
also have to take into consideration added weight. and the effects it may have.
it would depend on what tools you want to carry aswell.
that would be a big deciding factor. and what else you want to use it for.
