Originally, I was using 3mm Black nylon spacers between the Brook UFBs and the mount to give clearance to the solder side. They work fine but they are a bit fiddly to install and they are pretty expensive for what they are. I've made a couple more of the mounts for people recently so I thought I would print some spacers/standoffs instead. Two are required per UFB but the same part can be used at both ends.
Original spacers vs printed parts:
Original spacers (LHS) vs printed parts (RHS) installed:
They work really well and are much easier to install.
Files have been added to the Printables page linked to in the OP.