Hi Greg,
Congratulations in your endeavour, just need to readjust your time scale for deliverables. You will find this exercise very rewarding to have in the end a very comfortable machine, working as you need it to work.
I went through this exercise many years back, and your to do list is basically the same than mine but 6 years later. I purchased the second Xenon that arrived in the country with the first one (known as the Red Machine), and mine is the white "sister". The difference is that I bought a brand new 914 standard stock, so it is a RT.
It was meant to be a complete kit, but in the end probably only 30%. That was a blessing because it forced me to do my thing and being a kit, the law is quite different to your freedom. It was a great success and I have basically not touched anything since my first flight.
The list : Pedals linkage, false floor for heels resting allowing tool compartment, Rudder Teleflex cables with rod end bearings, and complete redesign of angles between the nose wheel, pedals and rudders. The end result, very light on pedals and it can turn on a ticky. Complete new schematics as the recommended wiring had many flaws. 13 fuses are in the circuit compared to the original 5. Push one button and leds confirm all fuses. In those days, Xenons were losing their doors in flight, and according to the french boffin, it was a pilot error ! I made proper carbon fibre frames for the doors and designed the latches. Of course, gas struts.
Instrument panel clogging, like you noticed called for an overhead panel with all switches that are not used often in flight. Don't worry, it does not affect visibility. Like you have said, EFIS is an issue when it goes to sleep, and I currently have that issue, rarely but it is there. Recycle power in flight because the MGL hangs requires full trust in your "feelings" to continue your flight.
Fuel circuit is an individual switch for each pump, and a 3rd for long range tank feeding in flight to the mains. Also a tap for filter service.
Carb choke is a bicycle gear lever fitted behind the pax seat. Used only once per day should not be on the centre console. I have designed a mechanism to use the old choke lever (blue control) to lock the rotors forward (anti gust). The rotor brake is nor very efficient, so I am using bicycle brake shoes that are far better.
I have redesigned the hub bar to give a 2 degree angle of attack instead of 1.5 and extended my short rotors by another 20 cm.
While I was building, all Xenons flying in SA had a oil overheating problem. So I decided to change few things before I would follow the trend. Water radiators are incorrectly mounted. Should face the air flow at least 45 degrees. Other gyros "cured" the problem by having 2 oil radiators. In my test flights, and using only the original small radiator, I noticed my engine running too cold (65 degrees only). I had to mount a thermostat to keep the oil at 90 degrees. Also, everyone thinks that by "ramming" cold air to the engine compartment helps. I chose a different method. Extracting hot air does the trick.
Of course it also has cup holders, and cigarette lighter socket to warm up coffee in flight.
The next job is to find a way to pee in flight !
Please understand that you are tackling this work to make your machine more comfortable to your liking, and your liking only. Unfortunately your Xenon will not gain value on the market because of these features. People do not appreciate and do not compare apples with apples. It is only for your own love.
All the best.