Quite a wish list?
Some of the solutions on your wish list are firmly in your hands!
Screws* Reduce the number of kinds of screws!
You can use all the same length of screws if you don't mind the extra weight.
No one keeps you from using #8s instead of #6s.
Wiring
* It’s really hard to run additional wires out through the wings or into the tail cone. That’s why I’m not updating to LEDs.
That is something a builder will have to decide, you want to run extra conduits for future upgrades, no one is keeping you from doing so.
My wing wiring can be completely disconnected at the wing root, Vans had nothing to do with that.
You can build a big acces door if you want to spend the time and money, most of us are pretty happy with the standard set up.
Can't think of an airplane that can leave the cowling on to pull the plugs???
Check the brake fluid...If your brakes don't leak, once a year would be enough to check fluid levels, two or three times perhaps when you change the oil.
Oil filter mess is something Mr Lycoming would have to address, me thinks, or simply adapt a good technique.
Miscellaneous
* Have a windshield defroster, even if it’s just an avionics cooling fan
* Provision for camera mounts and possibly wiring. Lotsa folks doing that these days
* Backup power for the elevator trim. (Electric trim is part of the autopilot)
* Swing out motor mount?
* High flap extension speed for deceleration at busy airports
* Cowl *easily* removable by one person, and replaceable, too.
* Reduce hiding places for dropped items on the floor. As much as possible, make the floor completely flat and smooth so that it is easy to clean.
* I have 2 windshield defrosters in my 10, feel free to install one or two.
* Swing out motor mount?? plus quick disconnects on all your throttle mixture and governor cables as well as all your electrical and other connections???
* Plan ahead to slow down or build speed brakes, I have seen them on an RV.
* Who knows, maybe the floor is actually flat on the RV 15, we haven't seen it yet.
I agree that easier access to maintain may be more important on the RV-15 but most of what I see on the wish list is up to the builder.
I am very curious what this new RV-15 can do and I am sure we'll hear about it once it has arrived in OSH