According to Dave's reports he eventually wired the fog switch up as per provisions made in the MMC loom. This takes a feed from fuse 12 (7.5 amp) labelled as "o/s sidelights and dash illumination". Clearly there is a need to uprate this fuse. The extra current flowing through it has no bearing on the PCB. Dave's recent issue was because he thought he could manage without uprating this fuse. See my post
here from over a year ago.
I would have been inclined to avoid the complexity of an extra relay despite the extra current for fog lights flowing through sidelight circuit, as it's switch contacts are designed to handle the higher current from headlamps, but accept it's a matter of personal choice. Irrelevant now since LED's being used though.
I think the inrush current issue you mentioned is relevant only to far larger LED installations.
