For anyone who is interested I've uploaded the Beta version of the domain rules to my Patreon. It's a free download and open to the public. I've used the Rules Cyclopedia as a starting point. Some of what I have done includes:
*Clarified rules for retainers, and explained how they become useful once domain level play begins.
*Tied land values to terrain type, rather than having the values randomly determined, but also allowed for additional resources to be discovered during play than can add to a hex's land value.
*Included some differing complexity options for determining income.
*Included rules for urban settlements.
The rules are very much tied to B/X but should be applicable to pretty much all OSR systems with similar economic assumptions.