If this is year 12 for you then I would think you have a very solid knowledge of what you like and don't like. If the price seems right and you can afford it, then go for it.
RV lots are definitely over priced for what you get as far as land is concerned, but there are other things involved that you're really buying that you can't get with other types of real estate. The biggest one is community.
When you're "over the hill" you can either leave your rig on the lot or build to suit. Your heirs will be stuck with it one day, but really all it is, is a piece of land with minimal HOA fees. Not that big of a deal for them to handle.
Only thing I suggest is watch out for the location. Brownsville use to be the place to go, now you hear very little about it. There's a nice little park there that the lot owners I bump into are always trying to sell because they are afraid it might go down during their time there. So that's one of those "there's a lot of lots available" places.
In Port Isabel the owners of lots in one RV park get hit with charges to dredge the channel and now may be faced with assessments for replacing a swing bridge. Both are very expensive and can surprise a new owner.
RV lot ownership is much like any other real estate investment, they come with risks. You might want to rent for a couple of winters just to get that insider knowledge.