My gravel thing has a dropper post and a little saddle bag. I’d like to attach a rear light to the seatpost just above the seat clamp (where I’ve got about an inch of seatpost showing before the dropper collar). But with the seat dropped there is only about an inch of clearance to the saddle bag, so it neds to be low profile. All the ones I’ve found so far stick out a fair bit at the back. Any ideas?

Lezyne Zecto, probably about 35mm deep, not used mine a lot yet but sees, quite bright

See sense Ace should work
https://seesense.cc/products/see-sense-ace-front-and-rear-set

Thanks both. Looks as though they could both do the job, although the Lezyne is a fair bit cheaper as the Ace seems to only come as a pair (I’ve got an exposure front light).

Lezyne Femto drive is pretty good, bright and small, I use mine on flashing modes in the daytime and steady or pulse at night.
I had a Lezyne Zecto but it died when water got inside and the usb port corroded, the little rubber flap that covers the port is a terrible design, the Femto has a screw on cover and is really waterproof.
The only issue with the Femto is the back, where it clamps on the seat post, is plastic so it needs a bit of foam or rubber tape to stop it moving around.
Edit: it sticks out about 35mm from the post.