Personally I think the first thing your BIL needs to consider is what he plans to do when he travels and how long he can devote to traveling. You mentioned that within a year, they both will be retired. Does that mean that they may want to full time? Does it mean that they may want to travel away from their permanent home a month or two a year? What do they want to see when they travel? Do they have pets that they want to take with them? Would they be happy traveling to only places they can drive? Would they enjoy driving a motor home, as opposed to an automobile?
Will both of them be driving? This means the driving task is shared between the two of them. Are both of them physically fit enough to bounce around in a motor home for a few hundred miles a day? Do they require regular visits to a doctor?
The answers to these questions will help him determine if a motor home is really worth the hassle? There is no doubt that a motor home can be fun but it can also require more maintenance than his stick home.
Motor home travel is also NOT cheap. In most cases, you can take a plane or train and get to the destination for less cost than to drive by motor home. If seeing the sights along the way are important, than a motor home is hard to beat, especially if they have pets. Without pets, I can travel and still see the sights better in an automobile. The money saved in fuel, insurance, required maintenance, and in RV parks will pay for a room along the way if traveling by automobile. At one point, when fuel was more expensive than it is today, I was spending around $200/day just for diesel. Not an insignificant expense if you travel a lot, as opposed to just sitting in an RV park.
You BIL really needs to consider a lot of things before he jumps in to an RV. It just may not be for him, regardless of the costs involved, IMHO.
