We can't know just how "handy" you consider yourself, but if you can take care of simple maintenance around the house, then you can make most "upgrades" yourself at about a quarter of the cost of having a dealer do it.
Adding a Fantastic Fan is probably a dealer job since it involves water seal at a roof penetration, but most other things are simple jobs, Adding towel rods, coat hooks, sliding baskets in a pantry, night lights at floor level, sewer hose carrier, hooks and brackets in the storage areas. All easily doable as DIY projects and you gain the advantage of knowing how it was assembled.
You will have to get creative at times because of the type of wall construction used in RVs but a little thought will produce solutions.
I like the idea of writing things down and not making a revision until the "want" has appeared three times on the list.
In the mean time, have fun out there.
PS: A good credit card and a nearby Lowes or Wal-Mart go a long way toward solving most things you run into.
PPS: Driveway camping for a couple of weekends will identify most of the things that need immediate attention. A lot more convenient than finding out about something while at Big Bend or Fort Davis.
