Do exercise caution using electric space heaters (or other high-current appliances) with the typical RV outlets. If the plug is getting more than a tiny bit warm, use a different outlet or preferably upgrade/replace the outlet with a good quality spec grade one. The connection between the common RV outlets and the Romex (a sort of vampire tap arrangement) isn't always the best electrically.
For overnight heat, if it's not too cold, you might want to consider an electric blanket or electric mattress pad.