Firstly I had to lay out the UV's in various UDIMs and do some texture tests to figure out the resolution I was going for. Initially I thought that 4096 would hold up with 6 UDIMs but it did not do so at all. So in the end we decided to go with 6x8192 tiles which holds up nicely from the pilots perspective. Should there be any close-up's needed it's easier to make textures specifically for that shot.
Secondly and most importantly I've switched renderers to V-ray and ditched Mental Ray for a number of reasons. Most importantly are render times since when Autodesk took over Mental Ray and made it standard in 3Dsmax they've stopped optimising it pretty much over the years. This means that Mental Ray as an "out of the box" renderer in 3Dsmax, while it gives nice results, is pretty slow. Now granted that I'm still figuring out V-ray (last time I used it was around 2008 I think) and I'm still optimising the settings, I've already greatly decreased render times.
Another reason for switching is that Mental-Ray, because it uses Max's standard interface, has a very convoluted way of setting up shaders that use Multi-UDIM textures. You basically have to make a comp material and set the offset for each UDIM seperately, which is a huge pain in the b*t. Couple that with the fact that using multiple large maps really seems to upset it in both render times and memory usage. V-ray uses the simple
Lastly, more and more studios (and thus more and more potential employers) are starting to use V-ray or are already using it. So from a personal development point of view it's good for me to also learn new things ;)
I've also started texturing obviously and so far I'm putting in the basic COL map (clean version) with all the dials etc. in. Have got a basic SPECR and also OPAC for the glass. Nothing fancy yet but it's starting to look ok :)
Keep in mind it's basic textures and I'm still figuring out the quirks in shading etc.