first and foremost i would actually try diving with it...youre worried it might slip off, but it doesnt sound like youve actually tried it in the water to see if thats likely, you could be trying to find a solution to a problem that doesnt exist.
if it does turn out to be an issue, i would try rigging it up with bungie cords..the cords were used specifically to deal with the compression of wetsuits at depth......plus youll likely have 2 or more loops of bungie, so the chances of them all falling off without you noticing is pretty slim (especially if you are checking it often)
if those are both still giving you issues you can always try diving with gloves, thatll increase some thickness around your hands and give you a nice lip where it overlaps your wetsuit.
i really dont see the need to complicate the issue any more than it needs to be.