I did a quick sketch[1] to illustrate... Will it work better for you? Perhaps a bit more merge work but seems could be done in similar amount of time but more enjoyable..
The problem is those bugfixes are often impossible for me to isolate and extract out of a new GPL release and reapply on what would be a stable branch. So, the stable branch wouldn't really get more stable than a development branch. A lot of the issues can only be fixed by merging the whole new GPL.
That forked development model works great when 100% of the code is under your control, and everything gets merged as separate commits. It makes it easy then to cherry pick fixes and merge them back into a separate branch. I can't do that with the all-or-nothing GPL releases.