Penni,
Claude is correct. There are multiple ways to pass that request to Disney.
When you make your ressie, if you call you can add a note on your ressie that reads something like "Close to Comfort Station". If you use the on-line tool to reserve, call back at some point and add the note.
Before arrival you can also go on-line on the Disney site and access your reservation 30-60 days before arrival (can't remember) to do the early check-in (give them your credit card number if you want to, etc) but you can also make some limited requests. They offer choices like "close to beach", "close to a bus stop", "loop 700", "near pet park", and others. The "close to a comfort station" is a choice also. If you don't do the early checkin that way, you'll receive an email about 10 days before arrival offering to let you do so. It is not required of course but it does reduce the time once you get to the checkin window at the Fort.
So you have at least two avenues and Disney seems to do their best to honor requests. No worries.
Bama Ed
PS - so you're in Dayton? Went thru there a few years ago to visit the big Air Force museum, the Wright Brothers Flying Field and the National Park History Museum for the Wrights. The flying field was cool. That was where they perfected their flying machine. Been to Kitty Hawk too (got a speeding ticket

) And yes, I am a technology nerd....