install stage0 libraries?

If I understand correctly, the way Hadrian works is that all of the .conf files, binaries, and so on in _build/stage0 are built with the bootstrap compiler. I need to write client code that uses the ghc library built from GHC HEAD (so ghc-9.3), but I'd prefer to use the bootstrap compiler. (The HLS works with the bootstrap compiler.) Is there a way to get Hadrian to install the stage0 libraries in a way that cabal-install can find it using standard options? I tried to do it myself using `ghc-pkg register`, and all I accomplished was to make an unrecoverable mess of my system. (The problem I'm trying to solve is to get my client code to compile against the latest library, while also enabling the HLS to find all the things.) Norman