I ended up creating a contraption that housed a 12 volt battery, inverter, and battery charger inside a watertight ammo box.
Step 1: Materials
-Power Inverter: Cobra CPI 480, 400 Watt ($26)
-12 Volt Deep Cycle Led Acid Battery: Factory Second 35Ah Sealed GEL Battery ($45)
-12 volt Battery Charger: Bass Pro Shops XPS i 5 ($72)
These parts are not too specific. I listed what each part is, then what I used and the price I got it for. All the things above I purchased on sale or with some discount (thrifty shopper).
Check online for an inverter, I found mine at amazon on sale at half price.
Get a Factory Second Battery. It may sound like a bad thing, but to those of you who aren't too familiar, a factory second or 'blem' battery is one that is cosmetically damaged, but otherwise fine. Buying a battery this way saves you at least half, which is upwards of $50. Also, don't get a GEL battery like I did. Get an AGM battery if you can. GEL batteries take a special charger because they charge at a different voltage.
I lucked out with the battery charger. I bought it in store with a 20% discount, and it charges GEL and Regular Led Acid / AGM batteries.
-Ammo Can: Find one that fits all your components. Mine is a long low 40 mm ammo can. 17" x 6.5" x 10.5"
-8 Gauge Wire: *It's important to have a heavy gauge wire to handle the large current load from the battery to inverter!*
-8 Gauge Ring Terminals
-Heavy Amperage Switch (Mine is a 50A from radioshack)
-40 Amp Marine Circuit Breaker
-1/8" Carriage Bolts, Nuts & Washers.
-1/2" Angle Iron
-1/2" Flat Aluminum Stock
-3/8" Threaded Rod
-1/4 20 Nuts & Bolts (Battery Terminals)