Not sure how active the rope solo scene is on fedi, but I figure I'd ask. There's been quite a bit of discussion over the years about various systems, but the modern consensus seems to be to use two progress capture devices on a single (or dual) fixed line, with one suspended higher than the other via use of a neck strap or chest harness. By far (at least in North America) the consensus seems to be to use the Petzl Microtraxion. The Edelrid Spoc seems to be a good alternative, is both lighter and cheaper, and is also mentioned occasionally in discussions about TRS. Brent Barghahn is seen in this photo in a double-Spoc setup: Any potential problems I should be considering?
b_g
I use microtraction, an old ushba and a homemade neck/elastic loop. Works fine. Ushba is primary, micro traction is secondary. Very smooth. Pay close attention to how your system performs in overhanging terrrain.