^WD40, may I comment on your mods and offer some advice in areas I'm fairly skilled in?
I was interested in your use of 0w-20 oil in your engine AND transmission.
Honda Genuine MTF is better for your VX if you want a 20 at operating temp(the first number only indicates how well it responds to colder temperatures, 5w-20 and 0w-20 is essentially the same thing), and it is a 5w-20 essentially; so you are really better off with their MTF for the sake of your syncros at least. However, I'd love to see a UOA of your 0w-20 oil changes.
Could you get a sample at your next oil change? In Canada, most heavy-duty truck service stations have Toromont CAT analysis kits from other oil experts I talk with. A sample tested is anywhere from $15-$30 US, not sure about the exact total.
Anyway, just to compare my UOA results using 0w-30 synthetic to your 0w-20. Of course, I'm in a warmer environment and my engine gets up to operating temperature slightly faster among other things. Just curious. However, if I could use 0w-20 in the winter here based on your UOA results, I'd consider doing that.
For your planned 'deep cycle battery', please don't get Optima. Get something like an Odyssey battery if you are going for a niche battery. In relation to that, an alternator kill switch? The VX already utilizes an eco charging system, as I'm sure you know, and is governed by the ECU. No sense in saving fuel if you have to replace battery more often or the alternator if it's fighting to recharge a battery that is fighting a no-recharge condition occasionally. Just commenting on your future mods, anyway, carry on. Unless, of course, you're doing the work of utilizing the kill switch plan for the alternator when you have the solar 12 volt panel on a bright sunny day working for you.
PS: Due to engine mounts needing replacement and ball joints/bushings needing inspection or replacement also, I have not pushed the PSI up on my newer 175 Destiny/Harmony/X-radial tires.