Hi @markstanley, this project looks really interesting. How is the status of it?
There is a GPS grabbing technology called "Fastloc", that will grab the sky for 30ms? and return raw data that can be computed later in the server. This tech grabs very fast, computes raw for about 12sec and then goes to deep sleep/off.
Every time it starts, it is a cold start but does not need almost a minute to gather ephemeris/etc.
Fastloc is probably too costly and heavy for your project, but I just wanted to mention it to you.
I have experience with it tracking sea mammals.