A couple of recennt threads got me wondering why you do not release Limerock as official DLC?
The game engine already has a 'mods' section so I assume it can manage licence additions OK and official DLC would generate an alternative income stream and interest especially once the game reaches V1 release.
The base GPB licence is very reasonably priced and official content takes a lot of time and effort to produce (doing it as a 'real' full time job rather than modding as a hobby) so a nominal fee does not seem unreasonable to me.