Baking two displacement maps seems like it is too much? It is pretty common to do that actually...
The whole internet isn't clueless on how to do this. It has been done before and you can find out how to do it by doing a quick search here on and on sidefx. https://vimeo.com/160341035
http://forums.odforce.net/topic/26234-ocean-displacement-intensity/
Both of those links should get you more than enough information to get started.