I wouldent attach anything to the wooden deck on a trailer much less a car you care about. 
i would only anchor it to the steel frame or an under-brace. 
I haven't seen the wood floor in person yet. Been thinking thru-bolts and even a fresh 2x backer underneath might be a better Idea for the wheel stops.
Straps will definitely be attached to the steel frame of the trailer. Thanks for the tips!
Jon
