I'm looking to get rear bike light suggestions with the following requirements:

Compatible for a road bike with aero seatpost. It does not need to fit around a TT seatpost.

Minimalist design and light weight.

Rechargable

Lumens- it does not need a daylight mode or be super bright- but I need a night time group ride friendly mode(s)- such as 30 lumens or less.

Battery life- 5 hours or longer on group ride friendly mode(s).

I already have a very bright rear light for solo riding.

Any suggestions?

Thanks.