Shirley's plan is exactly what we do as well. Our
Scamp has an icebox, but it isn't very efficient compared to a good portable ice chest. Since we cook outside anyway, we use the portable ice chest for cold storage and the inside icebox for temperature-stabilized storage of things like bread, chips, crackers, and produce (most of which doesn't really need or like ice anyway). BTW, be careful how and where you store canned goods, since things bounce around in a trailer, and more if your
axle is nearing the end of its lifespan. Low is good. We put ours under the front sofa.
Back to the missing cooler… In your case, I'd say try out the (far!) cheaper solution first. If it works for you, great! If it doesn't, you can start planning for the upgrade later.
If you want to put an actual icebox in the hole, they're available from
Scamp and also from other online sources, $100-120 as I recall. Scamp's shipping is expensive, so I'd look elsewhere first.* If you do, make sure you install the drain tube running through a hole OUTSIDE the trailer.
OTOH, if you are only going to use the space for dry storage for now, rig up some shelves inside and put a door (or even a curtain) over the opening. Keep it simple, and start camping!
EDIT - found some links in case you're interested… Looks like Scamp may be the better deal after all…
http://www.scamptrailers.com/parts-s...lts,16-15.html
http://www.vintagetrailersupply.com/..._p/vts-712.htm