For your purposes, I would recommend a 3000 watt generator. Electric heaters put a considerable load on the gen, also you might want to run a few other appliances. 3000 watts would even run an RV-type roof air conditioner, I have seen them mounted on road tractors alot.
Honda and Yamaha make quiet generators that are expensive. "Contractor grade" generators like Coleman, Generac, Craftsman, etc. are much cheaper but loud enough to bother those around you. A happy medium that many RV'ers have found is a brand called Champion. There is a LONG thread on an Rv forum about these types of gens here:
http://www.rv.net/forum/index.cfm/fu...d/15131645.cfm
The Champion 3500W gen that most of us prefer can be bought at many Tractor Supply Stores and Cabelas stores, but they can be found cheaper on this website for partsamerica.com :
http://www.partsamerica.com/ProductL...For=Generators
Scroll down to the yellow generator Champion part # 46540, that's the one many of us like, 3500 watts. This gen is alot quieter than the loud brands, but not quite as quiet as a Honda or Yamaha. Remember that most portable gens use a little oil and will shut down if the get a little low, so check it frequently. Also you know that you will have to have a source for gasoline, obviously most truckstops sell gas. Be sure you buy a gen that has a large enough fuel tank to get you through the night, some smaller gens of 1000-2000 watts won't hold enough fuel and might not produce enough power for your needs. A typical 3000 gen will weigh around 80-100 pounds. Here is a link to Champion's own website:
http://www.cpeauto.com/generators.htm