For Proton-5.0-7, this addresses a Scrap Mechanic crash relating to ValveSoftware#2165 where SteamNetworkingSockets008 is not a defined interface. It's the fastest-loading (for this game) Debian Steam packaged version of Proton, with my edits to add the SDK 148 methods for SteamNetworkingSockets008.
Installation instructions are similar to https://github.com/GloriousEggroll/proton-ge-custom:
Extract to ~/.steam/root/compatibilitytools.d/, restart steam and select proton-5.0-7-sdk148 in the list of Steam Play compatibility options.
Note: If you are experiencing extremely long load times, Proton 4.11-13 seems to work best from my testing. You can grab that here: https://github.com/stevenlafl/Proton/releases/tag/proton-4.11-13-sdk-148