We travel with my service dogs (one retired, one successor) all the time. When we are on the road in our truck, we use hard-sided, steel Variocage kennels (
see link here). If your truck interior is big enough, you may be able to fit one large one in the back of the cab. Depending on how large your dogs are, you may be able to fit one M/L sized dog and one smaller dog in one kennel, but that gets risky in the event of an accident.
A second option is to use Variocage-type kennels in the bed of the truck. Again, the hard sided, metal kennels bolted to the bed are safest (and most commonly used by service dog owners, trainers, and hunters), but I suppose a hard sided plastic kennel will do if you have a shell. It won't be as safe though and likely the dog will get killed in the even of a roll or crush accident. Be aware that, if your dogs aren't trained for riding in a kennel in the back of a truck, it can be quite stressful for them. Also, consider weather conditions and make sure that the kennels are well ventilated and cooled in the summer and insulated/heated in the winter.
If you choose not to go the kennel route, consider getting a proper seat belt system in place inside your truck. It usually anchors to the seat belt in your car and connects to a harness rig on the dog. NEVER connect a canine seat belt to a dog's collar. Always use an approved harness. Consider also that dogs in accidents can get fearful and run off, protective of their people and inhibit human rescue and treatment, or fierce when they are injured themselves. Kennels are usually the best option.
If you drive an RV (not a 5th wheel or TT), use crates in the back. Do not let the dogs roam freely in the vehicle.
When you arrive at an RV site, first, make sure that they allow your dogs and 2) that they are always on leash. We frequently use a 4' high X-pen (exercise pen) system that is connected to our trailer and anchored to the ground with 4' heavy rebar posts to use as an enclosed dog run. The dogs can exit the trailer into the enclosed run set up by the X-pens. The trailer side of the X-pen run is 24" high so that the dogs do not get under the trailer.
Do not let your dogs outside your RV or trailer in the X-pen unless they are directly supervised. Neither my 85lb Chesapeake nor 40lb mutt have cleared it, but they have been trained to behave around people, so consider how well your dogs are trained, as well. Be sure to deter barking or protective behavior (fence aggression) and use wire kennels inside your trailer.
I don't have any photos of our setup right now, but I'm heading to a dog show in Boise in about two weeks and could post some photos then, if you're interested. This X-pen set-up is very common at dog shows (hundreds of dogs in RV parks) and we very seldom have any loose dogs or dangerous incidents.
