IMHO: It is beyond absurd that any RV would not come with a full size spare. Some manufacturers offer them as an option and the penny wise and pound foolish folks just don't bother. If you have no spare and the ERS folks finally show up you will not believe what they want for a new tire (if you are really lucky and they just "happen' to have one available).
Our used C did not have a spare and it was the first thing I added. With a bottle jack, jack stand, torque wrench, 100 psi compressor and a tire repair kit I am at least able and prepared, if not inclined to change it out myself, which is a nice option when the ERS folks say it will be an hour or 3 before they get to you alongside the interstate (or tell you to pound sand if the flat is one of your duallies or you happen to be in a campground. Yes folks some of the biggest names in ERS won't come to a CG or change out a dually).
As always.... opinions and YMMV. :C