Oh come on John just pick them up , put on the o'drill press and punch a hole in it.
No really: a guy could make an angle iron cage that fits between the wheelwells for them to set in so they dont slide around. A guy can build a top so they will be fastened down.
Now for mounting to the truck bed is something that will have to be worked out cause some of us have shortbeds and others have long. Also some have gooseneck balls and some dont?
Not to be nosey but is it cheaper then one of those water bags that fit in the bed? I think they will add about 600#.