We bought a portable one from Home Depot for under $100. It fits perfectly on the doghouse in the front of the RV - late model Bounders on the Workhorse chassis have a doghouse cover that is about an inch or so higher than the surrounding floor, and completely flat, so it works perfectly. When driving it sits under the dinette table.
Is it practical? Well it can heat up our 36 foot Bounder and keep it cozy in temperatures in the teens, and it does add a bit of ambience when the rain is pouring down outside and you're longing cozily inside!