I also like to use those small hooks with suction cups on them. Attach them to the outside of the trailer by the door for hanging leashes and messy dog towels.
Ooh, I like that idea. Brilliant! I even have two extras that I can use for that now.
True, a 13' is not huge for four people and a dog, but on the other hand, a lot of people set up a screen tent or an awning
(or both) and then cook and lounge outside - so maybe that's an idea (not that you said you were too crowded, but just in case). Also, some folks set up a tent for the kids to sleep in (depending on how old they are and if they would like that).
On the battery running down. Well, even if the battery is in top shape (which it likely isn't), one battery can run down faster than you think. I've lived on boats where we lived 24/7 on our battery power, and even with a "house bank" of four or six batteries, we had to watch our consumption. And we had solar
and wind generation.
I don't say this to discourage you, but only to let you know that it's not at all hard to run a single battery down, even just with lights
(with conventional bulbs). If you enjoy figuring, you CAN plan it all out so that you know what you have and what you're going to need. If not, just ignore the next section
Basically, everything electrical
draws a certain number of amps (which really means amps per hour). Any given battery stores a certain number of amp hours. You shouldn't run a battery below 50% charge (it greatly reduces its life). If you can keep it up to 60% so much the better. So if you have, say, a 100 amp hour battery, you really have 50 amp hours to play with (we're not counting recharging here).
So you can calculate the amp draw of things like lights
fan, water pumps, personal fan, etc. and compare that to your battery reserves. Then if you come up short after doing your calculations, you either need to use fewer amp hours, have a bigger battery, or recharge faster (or use slower).
Light bulbs can be real hogs, especially if you have two or three on at once. As others have mentioned, LED bulbs, cold cathode bulbs, etc. draw much less. We used kerosene lanterns quite a bit (that might not be so great in a small camper though). I've taken to wearing an LED headlamp (Petzl tactikka, like this one: http://www.amazon.com/Petzl-TacTikka-Headl...e/dp/B0007Q3R34
-- it runs forever on 3 AAA batteries and the light is always right where you want it (unless you are looking at someone you're talking to
If your bulbs or electrical
items list watts but not amps, you can convert to amps (which is what you want to use in your figuring). You simply take the listed watts and divide it by volts (in this case that would be 12). The answer is amps.
It sounds a bit complicated, but it's not that bad once you sit down with pencil and paper, and like a friend of mine says: "If you can't put a number on it, it's voodoo"
The second half of the equation is how much you're putting back into your battery(ies). The most practical ways for most small campers are either to plug in at a campground (and run a converter or charger) or to use a solar panel
But really (and this is backing up a bit), a lot depends on how you plan to camp most:
1) Full hookups all the time? Then plug in, burn 110v electricity with abandon and perhaps just put 110 volt items in your camper instead of 12 volt items.
2) Some hookups and some "dry camping"? Then you probably do want to keep the 12 volt items in your camper for when you dry camp. You now have two choices for when you are plugged in: You can either install a converter, and convert the campground's 110 volts to 12 volts and use your 12 volt stuff that way. Or, you can install a a 12 volt charger, and charge your battery with that, and then use battery power.
3) Mostly dry camping
(or another option for #2 scenario): Install a solar panel
to charge your battery and run your 12 volt items from that. This dovetails well with the 12-volt charger in #2.
There are also meters that can help you to know how much amperage you're drawing and how full your batteries are. One of these would be worthwhile, IMO, if you were going to camp on 12v most of the time or use the 12 volt charger scenario.
I hope this wasn't too lengthy or confusing...
Also I'm sure others here know more and can probably explain better.