If you don't want gas then it will have to be an electric heater which is the best choice anyway after the horror stories you hear about carbon monoxide poisoning. The main point is that you need to look at the wattage of the appliance first because a heater with a high KW energy output you will be limited to what other appliances you can use simultaneously such as an electric kettle etc.
One shown in the link is 1.5 KW which should be sufficient to heat an 8' square area.
We have a Kampa electric bar heater. One bar is 400W and 2 bars together is 800W. Also, if it isn't on level ground, it cuts out as safety feature. If you wear some warm clothes too, it works fine.
The key point is not to make too big a demand on the electricity supply for your hook up. Any large / good camping outlet should have a good choice of heaters. Try looking at Attwools on line - they've got some suitable heaters.
------------- The greenest unit of energy is the one that never gets used.
Message posted by 664DaveS27/4/2017 at 10:43am Outfit: Hyundai Santa Fe -Bailey Unicorn Cadiz Location: Shropshire
Joined: 24/7/2007View ProfileReplyQuote
We have a ceramic element fan heater which does cold,1,2 and 3 Kw.
They were developed for heating aircraft while on the ground ,so are safe.
It also has a tilt switch to cut it off if it gets knocked.(we used to have a dog).
Had it for years,very effective.
------------- DS-There's more to life than football!!!