I will second the above in looking for Ken-Oscale.
He has made a lot of nice, interesting Fastrack plans in sizes quite similar to what you are wanting. Here's an Advanced Search on Ken-Oscale, Track Plan, and by Date. At the top of the search page (toward the right across from Search) there is a 'Show Search Query' you can click on if you want to see or change the search query. I have admired several of the plans Ken has posted, very nice for small areas!
I couldn't single out just the track plans in the search, so there are other posts mixed in throughout. At least there should be some you can find to look at. If Ken sees this he might even be able to help, I believe he's pretty generous about helping others with his plans and fitting them to their needs.
As another thought, if you are on a PC, there are two track layout design programs that you can try out for free and make a layout with up to (I think) 100 pieces of track. They are AnyRail and SCARM. Ken uses AnyRail, not sure if he has SCARM or not? I was just thinking that if you do find a plan you like, but want to make some revisions these might come in handy. Or you could even try your own if you choose to.
Good Luck in your search.