K Dog,
Any salt water spillage is fatal to metal, so extreme measures are necessary to prevent same. Personally, I've used a thick coating of underbody sealer on the floor of my van, on top of which is a thick rubber mat.
Having lost a trailer floor to salt water drips, I've learnt my lesson as I graduated to my van.
Also, any salt water lying in a pool in a van will evaporate, leading to a salty atmosphere which will corrode the van interior, usually in a place you can't see (until it breaks through). So, get the wet salty gear out to dry it AND coat the interior of the van with de-odourised fish oil as soon as you get the van. Wind-driven fans and a slightly-open window can help the airflow when stationary.
For those of you interested in Nissan Elgrandes, here's an outlet which sells them:
www.southernspecialvehicles.com.au/ErrorPages/404.html?aspxerrorpath=/compliance.html.