I use a vanilla Quicklisp installation. For some local directory trees I configure ASDF to prefer those trees over the standard Quicklisp versions by placing text like the following in my $HOME/.config/common-lisp/source-registry.conf file:
(:source-registry (:tree "/home/brown/toe/open-source/") ;; For swank.asd (:tree "/home/brown/local/software/source/slime/") :inherit-configuration)
+1 for this as the simplest path to the desired outcome.
./configure make sudo make install
and it works! I can put the clone anywhere I want. I can change it anyway I want. The system doesn't fight me.
that system is a struggle in so many other ways (dll hell; all the /usr/include stuff; etc...). and from all the various linux distros, precious few can achieve the equivalent of the CL ecosystem WRT reproducibility and fine-grained control over the versions of the dependencies (NixOS and Guix are the ones i'm aware of).
the seeming simplicity of that ./configure dance has an enormous cost that only shows up when it doesn't work in apparent or in covertly surprising ways.