Firstly, if you are not going to run a contact wire, then you cant run with the panto's fully up as they will snag your masts in spectacular fashion, so in this case, to make it look anything less than wrong, the panto's will need to be locked in a part way up position.
But personally, running masts and no wires, and pantos down, is comparable to having a shower with an umbrella up ! Why bother?
Regardless of it being powered or not,
If you are going to use a contact wire, the issue of mast spacing is also determined by the radius of any curves. The tighter the curve, for example 400mm radius, will necessitate the masts being spaced in such a way that so that the panto always maintains contact with the running wire as the train negotiates the curve, just like a real one, and has got nothing to do with making it look nice. Find a footbridge somewhere , preferably on a curve, and studyhow it works, and watch the panto as the contact wire zigs and zags from side to side.
As the radius increases, to say, 900mm radius, then the masts will understanderbly be able to be positioned further apart, while still maintaining correct alignment with the panto. (Within the limits of lengths of commercially available overhead contact wires.) Sommerfeldt has a number of different lengths, and you should consult the catalog.
Whilst there are a variety of masts and wire support structures in the real world, it may be necessary for you to work out beforehand , by doing a full size model plan in chalk on the shed floor, to determine what you will need to buy, and what you may need to fabricate to suit your particular track design. Then take a photo of it for reference once it has been walked away !
We have used Sommerfeldt masts and overhead wires on both "Fairfield" and "Coorparoo" and found it easy to install, once you understand what you are trying to acheive, and it is very reliable, with no failures after having now travelled thousands of miles to shows in the trailer.
Good luck, and thanks to Poath for his input too
And his brilliant video !
"Fairfield" and Coorparoo"