If you ARE able to find a camper that has a full size bathtub, you'll also need to make sure you have more than a 6 or 10 gallon water heater too. A 6 gallon water heater will not provide enough hot water to fill a normal bathtub. My last camper, the 6 gallon water heater was not big enough to even fill the kiddie size shower tub. (my current camper has a shower only).
As stated above, you might want to check into a park model. They also have larger water heaters.