Thanks for the complete picture. I think what BurkusCircus52 and I are both suggesting is that you start your yard with a switch on the outer main line close to the right-most crossover between the two main lines. Extend track off of that switch all the way to the point where your yard now begins and start building the yard off of your new track. This adds about 6 inches to your 8 foot side, but gives you a long enough yard lead to work the yard without interfering with the mainline, and it let's you use the two mainline crossovers as a "run-around" track so that an engine can go to the back of the train and push it into the yard.
In fact, if you are willing to add 1 foot to the 8 foot side, you could put two tracks out there, build your "run-around" track out there, and then never interfere with mainline operation while trains arrive and depart the yard. Might even put some engine service facilities along those two tracks?
My 02 cents worth of opinion.
Chuck
