Maybe, but most likely even the best RV mattress won't quite fit. One of the most common antique bed frame sizes is the ¾ bed, which is 48 by 75 inches long. They do make ¾ mattresses for an RV, but these can be either 75 or 80 inches long. RV fulls and RV short queens may or may not be the right dimensions for your bed either. No matter what size your antique bed says it is, the best thing to do is know its measurements before you purchase a mattress.