One thing that can save you a bunch of time is finding a good sketchup model that you can incorporate into your stadium. However, a lot of sketchup modelers don't paint both sides because, well, they're not importing it into OOTP. I've started a collection where I'm saving models I use frequently and have painted all the sides on, so hopefully they should import quickly and save you time on creating the lights, field, etc. You can find the link to the collection here:
https://3dwarehouse.sketchup.com/col...or-Use-in-OOTP