Factors to Consider When Installing Gas Tanks?

[Murrelet]

I've found some new tanks that will fit very nicely on either side of my splashwell. They are designed for below deck installation. Obviously, these would be installed above deck. I'm thinking thinking that this is not a big deal. Anything that that I should be aware of? Eventually I'm planning to build cabinets/boxes to hide the tanks and use as seats. I'm not planning on installing fuel gauges until this winter (fishing time is passing too fast), do I need to ground the tanks before then? I'm thinking that other than needing filler and vent accessories I can treat these as portable tanks , am I being naive?