As far as wire height goes, I run a Lionel stubby GG1 and a scale Williams, I am at least 5 1/4" up to 5/1/2" That leaves plenty of tension on both and it is kind of neat to see the pan go up and down under the different heights. For the first and last pole you are going to want to have them higher so the pan doesn't snag the wire and is eased into it....sort of like a trolley wire was when it went under a overpass.
Marty