My idea was to increase the yield on all resources and mix around the yield to keep it interesting, but I guess I need to do workarounds when it comes to culture.
Adding an own wheat build goes against what I'm trying to do in my mod, that bonus resources are nice, while luxury resources defines cities. However I guess I can add 2 food to wheat without improvement, then 1 food and 1 culture with improvement. I just have to add a unique farm improvement for wheat so that research does not mess up the stats.