I too know nothing about this particular company, but in general it looks that they rent some nicer Mercedes Sprinter based class B, B+, and C, generally in the 24-25 ft length range. These sorts of motorhomes are typically a little under 8 ft wide (7 ft 8 inch or so) not counting side mirrors, and between 9 and 10 ft tall. Compared to most modern Class A's (those built in the last 15 years) which are typically 102 inches (8 ft 6 inches) wide, with mirrors that stick out another 12 inches, and generally 12 - 13 ft tall, older Class A's built prior to about 2003 were often 96-98 inches wide, and about 1 ft shorter on height.
What does this mean in the real world, a standard full size parking space, like those you typically find in a big box store parking lot is generally 9 ft wide and 22 ft long. So one of these smaller sprinter based RV's could sort of fit in a single parking space without sticking out too much, and still with enough room to maybe open the doors with a regular sized vehicle in the next space. They could almost certainly fit in a standard parking space if allowed to overhang the curb, this means it is at least theoretically possible to get into lots of places a larger motorhome would not fit, now even though they are not as tall as most larger motorhomes, height is still going to be a limiting factor, and you will find yourself watching out for overhanging limbs, and other obstacles you don't normally notice when driving a normal car. Unfortunately the driver seating position is much like being in any normal van, so it is easy to forget how tall you are when driving one of these. Think of driving a class B or C as like walking around wearing a stove pipe hat, and trying to remember you don't fit through most door ways, vs a Class A with its higher driver seating position is like walking around on stilts and remembering you don't fit through most door ways. Either way you will not be driving through any fast food drive up windows, or parking in any parking garages.
As to the practicality of driving down the west coast I will leave that to someone else to comment on as I have not driven along the Pacific coast in over 25 years and I am sure things have changed.
