If you have a stale block, then it allows you to test things, while at the same time, it is not part of the heaviest chain, so it quickly disappears (and any assignable value is then lost, after a single confirmation).
It does not allow you to test things across long periods of time. It rather sounds like a complicated way to achieve a temporary regtest network.
However, the regtest starts sounding like the most appropriate way to resolve this problem. If we don't want the units of a network to become valuable, we need to simply make these networks abundant, instead of trying to ignore scarcity of tBTC, which is economic reality.