I'm continuing on with my take on the LPF shortcomings. Since others have determined the actual LPF are essentially ok in isolation, I have used the existing scheme but added relays on the ends of each filter. This adds 3 relays to the board.
This may not be the 'ideal' solution but I plan to get a PCB made and see what it does. Initially bench testing. It maintains the existing logic for switching also so no software changes are required in any of the flavours of software available now.
The PCB is designed to fit over the exiting LPF with all of those parts removed and transferred to the new board. A second mounting hole is drilled into the uBITX board for mounting also. While not ideal mechanically in that I have to remove all of the existing parts, especially the relays will be harder to remove . ( I only have a mechanical sucker and solder wick)
The new pcb has copper pours both sides and extensive vias either side of the tracks etc (195 in total vias) Obviously this is not a PCB to make at home! Schematic is attached and some screen shots also for constructive comment.