1 - My best suggestion is to take parachute cord, several lengths of 5ft to 10ft, (longer is OK).
Why you ask? After the final dive of the trip, everyone is in a scramble to rinse/clean dive gear and then find a place to hang everything or find an open space to lay gear on the deck in the sun. This process is more of a challenge if the boat is still moving (such as traveling back to port), &/or if there is a strong wind. In this case, anything that is not securely TIED DOWN will blow away.
And we all know that it's the "law of the sea" that gear only blows off the boat when there's no one around to see it happen..........
Attach your Boyancy Compensator (BC) to the rail by the shoulder clips; most safety sausages have clips on the end that can attach to something; most dive boots are heavy enough not to blow away.
Many people have had their wetsuits blown off of the boat because they only had them on a hanger on the top deck, most of the time the hanger was gone too. Hence the suggestion to take parachute cord. You can run the cord thru the arms (or legs) and tie the wetsuit, (or shirt, or whatever), to the rail without worry that something will blow away.
If you are not familiar with how to tie a great knot, just ask anyone on the boat.
2- Second suggestion - several large trash bags. If your gear doesn't dry, then put all of the wet stuff in trash bags before loading everything back in your suitcase. This will usually help keep everything else in your suitcase from also getting wet. Just remember to unload everything when you get home!