I know some people and even installers who basically designed a ground mount for a solar farm using free online tools like this online solar designer
which lets you set the roof pitch like you were saying, battery banks, inverter, service panels and everything then you get a price estimation on how much the system will cost. You can also estimate how much sun your roof will take using Google Tool call project sunroof https://www.google.com/get/sunroof
so you can plan which direction to face your panel and at what pitch to get the most sun.
But yeah it really depends on what you plan on doing whether you want to install the ground mount first or get a roof mount first. I think the project itself is pretty cool and bound to get really good return regardless of how big you make the system to be.