Camping in the driveway is the answer. Letting the dog know that the camper is part of the family surroundings and letting them get used to it parked with you there.
Whatever feeding time is in your house move it out to the camper and sit with the dog. Do this for several days and spend a couple nights out in the camper too.
Also add you leaving the camper for a few minutes at a time reassuring the dog you are just outside the camper.
I find too many people just up and throw a pet into a camper for the first time and drive off expecting a pet to understand the whole situation of being locked in a small box vehicle that is now moving down the highway. And when they don't, the owner takes the easy way out for 'them' and resorts to drugging the dog. :(
Pets need to be shown and get acquainted to the camper and know that it is a safe place to be with their owners BEFORE you head off down the road.
I have yet to come across a dog that was anxious, nervous, whatever that couldn't be calmed with TIME and EFFORT of behalf of the OWNER.
Best of luck helping your Sheba understand that the camper is a safe place to be.:C