So to paint you a mental picture, imagine a bunch of regular folks but with, like... more... beads?

Your being inclined toward less string clank might work to your disadvantage in this case: less noise, less overall brightness and volume.
My standard suggestions in these cases are:
1) if portability is a concern but bassiness isn't, consider getting a cheap resonator guitar and converting it to a 3-course (unisons or better yet octaves: eEaAdD) super-short bass. You'd have to source appropriately-dimensioned (large gauges but short winding length) custom strings, e.g. asking La Bella, via BassStringsOnline, for a bronze set with BEA
D gauges wound for 25" scale, then tuning it EAD
G. The bridge saddle should be replaced with a custom, compensated one or intonation would be poor up in the neck, but OTOH you could stick to the first frets and never venture up there;
2) if you know who to ask, have this big boy built
Loud enough ABG (kind of)
A fretless one should still be plenty loud.
Not the looks you expected? Well, the karindula bass suggested above seems to be similar in concept only more "authentic" (but I doubt it was invented earlier than a few decades ago).
Loud enough ABG (kind of)