Powerlite would be worth a look -
https://www.powerlite-units.com/lithium-ion-batteries.html
Got a PS30 in my Punto. Bought from the Green Spark Plug Company, asked them which they'd recommend for my usage and they went back to Powerlite with the enquiry.
Fitted spring time last year, occasional road and track use and was sat in the garage on charge when parked up, car has radio/alarm. Think I left it off charge for a week to test it, had no issues.
Dropped nearly 10kg after I'd modified the battery bracket to accept it, managed to fit a catch tank in the space it saved as well.
Tempted to say I could of got away with the PS20.
I accidentally left it off charge for two weeks at the start of this year, not sure if that has killed it or not yet. Put it back on charge and the car started after a couple of hours. Just going to cross my fingers til I bother to use it again and see how long it lasts off charge!