I'd have to see your setup, but I would not put reg below floor if it will pick up road debris.
Where is your tank mounted?
Keep regulator within a close proximity of the tank
I have seen high preasure manifold hoses up to 72" 's but I like to keep under 24" if at all possible, make sure you use a two stage rv type regulator and have the vent facing down.
DO NOT USE A BBQ REGULATOR!!!
If you need to mount the regulator sideways, buy a motorhome regulator with a 90' vent
Striaight for mounting vertical

90' for mounting horizontal

And you can get hoses up to 12' to come off the tee for your stove
But the kit i showed you comes with one and the tee has a shut off for the high preasure line, just perm mount to high preasure line with rubber coated clips along the frame to the back
http://www.campingworld.com/shopping/product/12-propane-hose-assembly-with-swivel-ends/3759All the quick connects I've come across are low preasure and after 29 years working on RV's, I don't trust any fitting to not leak, so high preasureing a low preasure device is taboo