Seems this method wouldn't work as well if you have external clients you deploy for. I'd use Docker instead of doing this, just to be in a better position for an internal or external client deployment.
If a company wants to use Docker that's their choice, but I don't think its at all reasonable to insist on or only support that environment as a software vendor. If it works on Debian, give me a .deb or even better an Apt Repo to use.
I'm looking to do something pretty similiar, but RPMs. I found rpmvenv that seems to work in the same fashion. https://pypi.python.org/pypi/rpmvenv/0.3.1