I thought I'd recorded the best bass tone ever on a track over the weekend using my non-reverse thunderbird with cobalt flats plugged straight into my focusrite interface and using a bass amp model and compressor built-into logic. It sounds awesome in the track — but when I solo the bass track it sounds all clanky and weird on its own.
You mentioned you looked at short scales, how about a JMJ mustang? They're great little basses that get a lot of praise — I like 'em so much I own three of them and out of all my basses they're the only ones that get taken to rehearsals & gigs.
Gibson really do seem to offer basses as a bit of an afterthought. They did a short scale thunderbird about a dozen years ago but only made 400 — all in black. If I had a spare £800 back then I'd have snapped one up. Surely there's a market for a run of short scale gibson basses now that aren't SGs.
The UK Gibson demo shop on reverb has one listed for £1,274.15 https://reverb.com/uk/item/70514505-gibson-non-reverse-thunderbird-faded-pelham-blue-demo
I just went looking for an image of the bass to use in the track header in logic (I do this for all of my guitars/basses/ukes) and found a source image at gear4music on this page: https://www.gear4music.com/Guitar-and-Bass/DISC-Gibson-Non-Reverse-Thunderbird-Faded-Pelham-Blue/40R7
If I am reading it right it looks like the bass might now be discontinued.