Outside of Eretz Yisrael, you do not need to affix a mezuza (even without a blessing) to an apartment, house, or other accommodation that you rent for less than 30 days.
If you are living in a rented house, apartment, RV, etc., and remove all of your possessions used for living (such as clothing, bedding, and toiletries) at some time before 30 days have elapsed, the place is not considered to be your domicile. You restart counting the 30 days from the day you move the personal items back inside. 
Situation You rent a vehicle for 30 or more days but live and sleep there only five days a week (and remove all your personal items to spend Fridays and Shabbats with a family or in a hotel)
What to Do You will not be considered to be living there; you must affix a mezuza only if you leave some personal effects in the vehicle continuously for at least 30 days.