I don't see why not, as long as you have sufficient heat insulation behind it so that the wood of the structure isn't affected. Static caravans I have rented in the past have always had a decent electrical supply to them, but sites probably vary so it would be best to check.
basically it will come down to fixing correctly as has been stated AND a decent electricity supply. if you have the fire belting out at 2kw, then turn the kettle on, bearing in mind you have appliances running in the background, tv, fridge etc. there is a very good chance that you could trip your supply (and possibly everyone elses if its shared supply)
an off the wall suggestion (assuming you want to move away from gas) is an inverter (Zibro type) paraffin heater or even more off the wall is a diesel heater - look on you tube at the chinese diesel heaters. ive bought one for our static in France, but wont get over to fit it this year