I guess without pics etc there is onyl a limited amount we can say, but my 2p's worth is:
1) make sure it;s well fixed down
2) make sure the fixings (that will inevitably go through the floor) are watertight
3) well worth doing a "dry run mock-up" before you start the treal work - I built an instrument console and went through 3 iterations tho get one that looked right, held all the toys and allowed me past to get to the bow! (the latter bing the one that resulted in the 3 iterations.....)
High level thought - forward = drier, but bouncier.