Shrinking/compressing Blu-ray ISO's?

[brake]

Hey guys, Currently in the process of backing up a lot of my Blu-rays, especially my favourites and steelbooks so they don't get damaged when I want to watch them.

I was just ripping the disc as an ISO and going to burn them onto a blank Blu-ray of the equivalent size which is fine as far as the main movie disc goes, but as for the other discs, EG: disc 2 and 3 that have special features, it's not really worth it wasting a 50GB Blank Blu-ray just for this... I would prefer to shrink the ISO down to 25GB or maybe even around 8GB for a Dual Layer DVD as I don't care about quality lost of special features.

I would like to keep it as an ISO so if I do shrink it to fit on DVD I can burn that smaller image straight onto the DVD and retain menu's etc (this should be possible I think)

I've already played around with makemkv, shrinking each track on the disc to an MKV but this can get finicky with 20+ tracks on a disc, I just want something like dvdshrink for Blu-rays where you can set the size, click it and walk away. Does anything like this exist?

Thanks!