I have been wondering about doing something like this due to it being a popular request. However there is one major difference in my planned implementation, which is that it should be added to WTP itself and enabled using the same approach as the 1/2 plot radius selection. Making a fork and maintaining both will result in development overhead and as time goes on, said overhead will only increase in size.
My plan for implementation is to do as much as possible using reusable code. The setting should be a game option, which can be set by a map option if needed. Game options will then gain the ability to apply a CivEffect to all players if enabled (so a future game option can do something similar using xml only). The added CivEffect will then list units, buildings, yields etc with an iAllow set to -1, which disables them. We would then have to finish the allow code ingame (it's half implemented), but considering that it would have to be finished to allow for the tech tree, it will have to be done eventually anyway. What's left is likely only the yield bar, which would require a rewrite to be able to handle both options. A rewrite is planned anyway since the whole colony screen code is horrible.
Yes it's more work to get up and running, but it will be much easier to maintain and the new code will by design allow other future projects.