Well I was going to suggest:
the Telemini, theEggfinder Mini, & the (almost here) Featherweight GPS.
Looks like that's been handled.
All excellent choices from great vendors/manufacturers.
Very different from each other, with a lot of factors to consider, but all great quality.
Telemini is by far the smallest/lightest overall package, but is not GPS (RDF telemetry only).
I've used this myself, and had great results.
Eggfinder Mini is an amazing price, but it is a kit that you have to solder together yourself (or get someone else to do it for you).
I've not flown this particular piece, but I've had great experience with other Egg products, and lots of other folks on this forum are very happy users.
Featherweight looks to be simply incredible in terms of functionality, and is a surprisingly good price, but it's not quite available just yet.
I've obviously not flown this particular piece, but I have lots of experience with other Featherweight products (Raven altimeters, AV components, mag switches, etc.) and honestly Featherweight products are second to none. Extremely well thought out, super high quality, and always unique functionality (as well as being super tiny).
Seems like the perfect time to be looking for tiny tracker options.
s6