I guess it depends on where you are going tomount them,I guess along the sills and one front and rear.
I would recommend,a fine drill bit and a few small self tappers.
At least this way you will be able to convert it back for whatever reason,and theres no waiting for the adhesive to set up,if you decided to bond them on.
I guess if you do drill and screw I'd recommend a blob of sealant around the screw hole to prevent the water getting in and rustt starting,but that should only affect you if you do a lot of river crossings.
I'm sure theres some closet neon posse on here to give you some advice :L

Darren