Hey Martin,
I have the 36mm LRGB SHO 3nm Antlia Pros with a QHY filter wheel and a QHY290m. They are awesome filters.
They are all parfocal (i.e you can focus with the L filter and that will be in focus for all the other filters). Keep in mind my focal length is only 600mm (waiting for my observatory build prior to upgrading scope). I have no issues with focusing when switching between filters. I focus once and then never again for the night.
I would get the 36mm. With your larger sensor (I only have the 290mm pro) then you will only cry once
.
Hope that helps,
Dilshan