I’m just going to blurt out my first thought as I’m in a hurry but want to give you pointers based on my experience with this:
Most likely not all the hull shapes can be unrolled, you will need to use squish to flatten them.
But generally it’s wise to first have a setup for the final decals bith in 3D and 2D. These can always be tweaked, but al least you know what is possible.
Maybe you better approach this from 3D to 2D .
Is the artwork graphical/vector based: Than you can draw,project,pull lines onto the hull to create the artwork lines in 3D.
The next step then would be to unroll/squish the hull as parts with the curves. I’d suggest to split the parts to flatten at areas with the least ‘going on’ graphics wise so when applying the decal the alignment is easier.
When you need a bitmap as decal:
My approach would be to create one single mesh for the hull first create a single mesh for the complete hull and already think of where this mesh is going to be divide into separate decal-parts.
If your hardware and software allow you can create a single image for the complete hull. But maybe you have to split your bitmaps into smaller parts because of memory limitations.(or work with low-res placeholder images)
Flattening the meshes could work with squish or scripted to align with an unroll but I’ve never done that actually, but I think it perfectly possible.
Do make sure to first test your complete workflow at the full scale and complexity of the decals, if you start an approach and you end up hitting a wall near the end you lose a lot of time and effort.
You can also use a hybrid bitmap/vector workflow, where you create 3D lines as reference and fill in the bitmaps on the flattened result.
Consult those producing and applying the decals they’ll have specific needs you need to be aware of while you create the decals. It can be as simple as shifting stuff a few meters to have seams free of artwork.
Anyway goodluck and keep us posted on the progress, always interesting to see this type of projhects develeop.
Maybe @hannesgrebin or @Steve_Howden can give you some general guidance as they have dealt with this type of stuff as well.