We slowly need to interface with an app at work that uses fixed-width too. It does not sound that bad if you hear it but it sucks to figure out where you are missing whitespace when most fields are not used and therefore all whitespace. Oh, and of course there are a lot of fields, also are aligned/formatted differently based on their type and has thin/no/wrong documentation. And I have yet to find a simple but decent “debugger”.
I am exposing docker via tcp in wsl and set the env var on the host to point to it. A bit more manual but if you don’t need anything special, it works too.