Thank you to everyone who offered suggestions.

I think I might have a go with some FB after all - having just developed a few sheets of Harman DP this evening, it's not as difficult to handle as I feared, albeit that it was in 5x4 rather than the 10x8 I'd prefer to be using for lith.

The issue of setting up for washing FB remains a bit irritating, though, (it's a faff to set up stacked trays in the sink, which is all I can think to do ... but that's a subject well covered elsewhere, of course)