I also travel by air (and company van) a few times a year for work.
If it's a new place that I haven't been too yet, I'll online search the area for hobby shops and craft shops in that destination area so I can get supplies as I need them.
If I fly then I only bring my model project. Either the whole kit(s) or sub-assemblies.
- also tweezers, files, sanding stuff
- I don't bring blades, paints, adhesives, putty
If driving, I'll bring my blades, adhesives and putty fillers.
I never paint "on the road" or do any final detailing. I'll only paint if I plan to be away for months