Full buffer/supply tank in front or back of trailer?

[Jordie]

Over the axle but regardless of whether wheels are in middle or closer to back?

[Ikii]

I would say over th e axle regardless of where they are.
This video is for weight distribution.

[Gus1]

I have mine right on top of my single axle trailer. Distributes the weight evenly throughout my trailer set up.

[Walterjn]

I always try for a balance point just in front of the axles personally. A little more tongue weight makes it a much smoother trip.