YXZ 1000r transmission oil

Central Texas
All right, I've got a question.

A bit of background: Yamaha makes a side-by-side called a YXZ1000r. The machine has a split sump between the transmission and engine: they don't share the same oil.
The transmission is a sequential dog box transmission with a wet clutch. Yamaha just states to use the same oil in the transmission as in the engine (API SG or higher, JASO MA) [Off topic: I don't know why they suggest a JASO MA oil in an engine sump that has no wet clutch, but maybe its just to prevent the servicer/owner from putting the wrong oil in the transmission?]

I can understand the JASO MA specification for yamaha to at least address a wet clutch.
The way I am seeing the transmission is that, being a sequential dog box transmission, what is needed to serve it is a GL-4 minimum benchmark.
Based on your knowledge and formulation experience, how would some of these perform in that sump with respect to the clutch and gear wear control:

1. conventional or synthetic GL-5 gear oil (boutique or off-the shelf)
2. conventional or synthetic synchromesh "MTL" GL-4 gear oil
3. Universal Tractor Hydraulic Fluid (UTTO) "for use in applications that call for GL-4 [and a listing of many others]"

As far as I can interpret and understand:
The GL-5 and GL-4 gear oils will definitely uphold the gear wear protection. I don't know their typical or relative performance for clutch frictional performance, nor if there is anything in either's usual/conventional formulations (off-the-shelf) that would outright chemically attack the clutch. To my knowledge, there is no specification for clutch performance in gear oils, but at the same time, I have a hard time believing that there is no prior history in decades past that we have used a wet clutch transmission and tried to tackle managing both with some kind of gear oil formulation, or where that development went. Probably a good intro to where I went next, which is below

Universal Tractor Hydraulic Fluids--these are pretty much a new wild card for me. All I have is statements on Traveller or Supertech bottles that say "for use in..." instead of "meets" and I don't know if I should trust the terminology to imply that it upholds a GL-4 level of protection. I would think that if there is anywhere where such a sump commonly exists, it would be the tractor or industrial machine realm.
I also have a YXZ1000 and IMO the gear oil would be ok for the gears but is a bad idea for the clutch. It will likely slip and burn the plates which can happen even using the correct oil due to bad usage. Yamaha recommenda a heavy multigrade motor oil for eng and trans. I have been using and would suggest M1 15-50 or Rotella T6 15-40 for both with zero issues being ridden hard. This oil has a decent dose of wear adds that are good for gears but not so much the clutch would chatter or slip. Ive been using this oil in wet clutch motorcycles for many years without issue. (One of the bikes is a Kawasaki H2). Dont overthink this, if you have doubts get the Yamaha oil and go ride.
NB Canada
I guess they recommend JASO MA for this engine because they already have that oil in the Yamalube lineup and they know it meets all the requirements for the engine, why would they complicate things with a new packaging.

What is the recommended viscosity for the transmission? If they recommend 10w40 JASO MA, I cannot see why you would use something else, except for availability restrictions.

If you want to be exotic you can buy specific gearbox oil compatible with wet clutch, Belray and Maxima have them. I tried the Maxima MTL Trans/Clutch Fluid in the gearbox of my Yamaha RD350 years ago, but I no longer use it because it is more expensive than conventional JASO MA and I couldn't really see any difference in performance.