Kala u-bass. 20" scale and they sound fantastic. Not real loud acoustically though, but there are small battery powered amps that work pretty well. There is a new acoustic bass coming soon or is already available called the shortbass. A bit larger than the u-bass but said to be pretty loud acoustically. There is a thread here on Talkbass about it.
I use a Jay Turser Mini P-bass. Light as a feather and fits in a regular guitar gig bag with room to spare. 30" scale so it feels exactly like playing one of my other shorties.
It sounds great and it's cheap so if it gets lost or broken it can be easily replaced.
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