There should be no problem with a battery lasting a weekend running a fridge, especially if you run the engine (fast-idle, or actual driving) for at least 10-30 minutes a day. Running the engine should recharge the battery to around 80% of it's capacity in fairly short time. It's that last 20% that takes forever and really affects the life of the battery if it's not done at least somewhat regularly (at least once a week or so while in use).
Also agreed, you need a "smart" (3-stage) charger with at least a 5-amp capability (10 would be even better) if you're going to do those top-off charges at home after your trip (not sure if Deltran has one that big, most of them I think are more around 1.5a).
Edit: This one here says 5 amp, so that would work.
http://www.amazon.com/Battery-Tender-022-0157-1-Waterproof-Charger/dp/B002DU3S9A/
Also best to keep the cables as short as possible (I see some extension cable crap being offered on that page, avoid).
I'm not aboard the AGM bandwagon for most applications myself... A good quality flooded battery usually serves just as well to power something like a fridge for a weekend (the difference in amp-hours between flooded and AGM batteries of a given size is only slight, flooded ones actually being about 5% higher on average). Only if I was really pounding that battery hard with vibration and impacts (jumping/rallying the vehicle, etc.) or if there was no way to avoid not mounting the battery upright would I spend the extra $$$ for an AGM. They just are not cost-effective otherwise.
I use Delco Voyager batteries because they are one of only a few flooded batteries that do not seep acid through their vents when jostled (so no corroded terminals, trays, etc.).