Yeah, the KEX pluging requires everything to be mapped to a single .TGA (Targa) file. 4096x4096 is my preferred size for this as it is the maximum resolution allowable by RF. You can use the same map on multiple materials (matte, gloss, metalic, etc.) but only one map file. There are also Specific naming conventions for different features. ~CS_SBS is the "show both sides" material. So if you have a single plane it will show the material on both sides. ~CS_CANOPY is just that... for canopies and windows. This helps with transparent rendering in RF. There can be lots of errors if you do not use this on your windowed materials. Then there is the ~CS_BREAKAPART which will only show that material when the airplane breaks... so art that looks like ripped film covering and such only shows when the airplane crashes. I'll not go into bump (normal) and specular maps but they are optional as well. If you are a graphic arts person you probably are familiar with these terms.
I was planning on using David's artwork as it is already pretty square and at a very high resolution. The parts are already mapped out so it would just be a matter of mapping them out correctly within MAX. I was planning on using normal unwrapping or unfold wrapping so that the surfaces could just be scaled and positioned. It would save a lot of work and I could do it just a couple of hours... if Max was working right in Windows 10.
So basically you just select a part, apply the UVW Unwrap modifier and edit the UV map all within Max. You can select multiple parts (canards, wings, etc.) to cut down the time and make sure they are scaled exactly the same and positioned close to each other on the map. just select the parts before you apply the modifier.
I have the RF model flying pretty realistically at this point. Went with a 70mm EDF on 4S as that seemed to be the most favored setup when it was released. Weights and aerodynamic tweaks are in as well as mixing, rates, and expo. I have a couple of modifications to the 3D mesh to make still. I positioned the EDF too far forward so all of that geometry needs to be re-located. Pretty easy to just move the verts. I dont think I'll bother with smoothing groups. This is such an angular airplane that it really does not need them.