I have done a bit more digging and have identified that this seems only to be an issue with composite sync and PAL TV sets. Sets that support PAL+NTSC (or just NTSC for that matter) do not seem to have the issue, many of these sets also allow you to set the RGB sync from PAL to NTSC in the menu.
I will give the sync stripper a go as suggested and I will see if I can find anyone that has built the PAL Horizontal sync fixer circuit.