I would run an inner strand of electric off the barbed wire at the very least with either offsets or run the track “double inside” - meaning use posts on both sides keeping them both off the barbed wire AND the opposite side.
Most people use some sort of step in post and tape or electric rope. Whatever you do, ensure you have emergency breakaways on them. If you make your track more of a curve you may be able to get away with all step ins (so make an oval inside of your square/rectangle).
You don’t say how many horses you have but I like two feeding stations at the very least to reduce competition and crowding. I’ve got 8 horses on my track and that works well for us.