Thanks for the suggestion.
On UPS: pipes aren't the cost they used to be. Factorio 2.0 reworked the fluid system so contiguous runs of pipe merge into a single segment and get computed as one unit. A long duct line costs roughly the same as a short one — the per-pipe cost that made this a real concern was a 1.1-era thing.
Also worth knowing: as of Plasma Beacon 1.0.2, HD Plasma Duct is no longer required. You can dock a plasma beacon straight onto a fusion reactor's plasma output and skip the piping entirely.
On a burner version: possible, but it opens a worse problem than it solves. A beacon prototype can't take a burner energy source, so the fuel has to sit on a hidden entity underneath the beacon. That part works — but there's then no way to see the fuel inventory. You'd be feeding a machine you can't open.
So it's on the list, but parked until the inventory side has a decent answer.
