I am remembering that the v5 board contains different transistors for the 45 MHz amplifier with a higher Ft (aka higher gain at 45 MHz). I get it that he worked the spur level in bite sized pieces. I can't speak too loudly since I have not have time to fix my own v4 in this problem, but sensing the pain of ordering 2 parts is why I suggested to Barry to try everything else first, and that shielding the leakage into the 45 MHz may be a bit more important than this amplifier type. I haven't looked at the 45 MHz filter on v5 - does it still use toroids?
I am thinking that implementing all of the v5 fixes on a v4 board will not necessarily - or likely cure its ills. my conclusion is that it is easier to cure a v4 board if you are willing to sacrifice several watts of CW output -- I decided I could not do that, and I don't need 15 to 10 meter SSB just yet with scarce sunspots. So I suggest that fixing the harmonics is a higher priority now - and here in the US we do have a supplier selling a kit to do that.
enjoy your radiations