ShortScale.org

There are tons of Start Tele clones but I'm having a hard time finding decent clones of the offsets.

Because there hardly are any.

Well depending on what you mean by "decent", there are the SX Liquid, the Xaviere XV-JM, the Jay Turser Surfmaster and of course, the Squier Jagmaster II and the Squier CV Duo-Sonic.

These are the only OG offset inspired currently in production models that I'm aware of.
They're all very much entry level instruments but once set up properly, I reckon they'd be perfectly suitable backup guitars.
They can be upgraded relatively easily but once you factor in the costs, you'll find yourself quickly catching up to Fender Blacktop money.

Beyond that, there are the Dipinto Galaxies which are Jag-ish, I suppose.

Fernandes and Charvel dabbled with the shape briefly but they are rare and in the Charvel Surfcasters case.. expensive. Jackson Surfcasters are less expensive.
Servicemen Jags can be bought cheaply but quality can be an issue.
There are a few new cheap brands that do a Jag shape like Wesley for instance. Stagg did one, but a lot of these are cheaply made.

Modifying a Jagmaster seems the best route.

italia make some interesting takes on the old 60s classic designs. The Modena is one of their takes on the shape http://www.italiaguitars.com/ but not sure about the scale length

Modenas are 25.5" scale.

Oh, and the Danelectro Dead-On 67 is somewhat Mustangy.