Babyblueyes (and crazylev, since this is your thread),
Your Bambi will probably come with two Interstate Battery SRM-24 Marine/RV batteries. These have 82 amp-hours each at a 5 amp discharge. You don't want to discharge them below 50% if you don't want to be replacing them more frequently, so instead of having 2 X 82AH, you have 82AH to play with, or 16.4 hours at a 5AH discharge rate. Battery capacity decreases in cold temperatures, and it decreases with higher discharge rates. When the voltage indicator on the Airstream monitor panel drops below 12 volts with the batteries being used (i.e. a fan running), you're at or below 50% charge.
Whether the 82AH 50% charge of the two batteries lasts more than a day, depends on your electrical use, and that depends, in part, on the weather.
The Fantastic Vent fan draws about 2 amps on Low, 2.5 on Medium, and 3.0 on high. You can do the multiplication from there. For example, if you run the fan on medium for 12 hours during the day, that's 12 hours X 2.5 amps = 30AH. If you add 12 hours on low at night, that's another 12 hourx X 2 amps = 24AH for a total of 54AH, leaving you 28AH for other things that day, before the batteries are down to 50% charge.
IIRC, the Bambi gas furnace fan draws 5 amps. If it runs an average of 2 minutes out of 4 for 12 hours at night (50% of the time), that's 12 hours X .5 X 5A = 30AH. If you add 12 hours of daytime use running an average of 1 minute out of 4 (25% of the time), that's 12 hours X .25 X 5A = 15AH for a total of 54AH. It might seem you should have 82AH - 54AH = 28AH for other things that day, but because it's cooler, the externally mounted batteries have less capacity. This is cool weather. The furnace can run much more than this (percentage of the time) in colder weather.
Each incandescent light bulb draws 1.4 amps, so one 2 bulb fixture draws 2.8 amps. Running only one 2-bulb lamp at a time for 5 hours, that's 5 hours X 2.8A = 14AH
Your water pump probably draws 6 amps at full flow, so running it for 2 minutes per night per person is 2/60 hours X 6A = .2AH with one person. Not much. In that 2 minutes, it can move as much as 5 gallons from the fresh water tank to the grey water tank. You can stretch that 2 minutes/5 gallons by using a lower flow. Water capacity used is much more important than the pump's electrical use.
There are things in your trailer than use little bits of electricity constantly, and these can add up. Any appliance with a circuit board draws a little constantly. That includes the refrigerator (even when run on gas), the water heater, the LP detector, the AM/FM radio (even when off). These can amount to several amp-hours.
And we haven't even talked about TV, DVD, satellite receiver, or radio usage yet. The TV antenna amplifier uses battery power so don't forget to turn it off when done.
Using 25-27AH per day, you should be able to go 3 days if little to no fan or furnace use is involved, and keep your batteries above 50% charge. If you don't mind replacing them 2 to 3 times more often, you can discharge deeper than that, but without an amp-hour meter, it's hard to tell how deeply you're discharging them. If you go to the point the 11 volt light goes out on the Airstream monitor panel, you're committing battery homicide. A battery is considered fully discharged at 10.5 volts.
Besides not being able to run your air-conditioner and hair-dryer, you will also not be able to run the microwave oven, without a generator. If you have the gas oven, the microwave isn't as important... but you can't bake bisquits or cornbread in a MW anyway, unless it's also a convection oven, which will also require a generator.
The nice thing about running a generator in the evenings is that the electricity for the light(s) (you can afford to run more than one at a time), water pump, TV, DVD, sat receiver, radio, AND MORE IMPORTANTLY, vent fan or furnace, doesn't come out of the batteries. It comes out of the converter along with the electricity that's charging the batteries. Besides feeding the converter during this time, the generator can be used to power the microwave and hair-dryer, as well as chargers for the rechargable batteries in the notebook computer, printer (Canon i70), cell phone, PDA, and digital camera or camcorder, and all these items can then be operated off their own batteries, rather than the trailer battery, when the generator isn't running.
If you run for 4 hours per night, the trailer batteries only have to supply 20 hours of vent fan or furnace use (plus music, TV etc).
The generator is setup next to the trailer, which is plugged into it with a 15A male to 30A female adapater. You can secure the generator to the trailer with a Kryptonite cable threaded through the slots in the trailer wheels and the generator handle. This isn't foolproof (someone can cut the generator handle) but it will stop the snatch and run crowd.
Since you don't have a truck, you won't be able to safely carry the generator, and a can of gas for it, in the tow vehicle. You don't want either of those in a passenger compartment with you, expecially in an accident. These will have to be secured inside the trailer somehow. You could skip the gas can if you use a siphon hose with a bulb and use the gas from the SUV to fill the generator.
Honda has restricted shipments to on-line vendors, so you may have to wait for an EU2000 generator. Many of us here have had good purchases from Mayberrys in NJ
, and many have been satisfied with Alamia in CO
Hope this helps,