A good question so I checked on my vixen neoachromat (hadnt got around to trying it yet)
In a word : no.
My 48-49mm adapter (fotek) screws onto the end of the flip mirror and is almost, but not quite, flush with the barrel of the flip mirror. When I try and then insert it into the focussing mechanism of the tube it is fractionally too wide.
Perhaps the lumicon step down ring will do better - if so please let me know.
Sorry to be the messenger of the frustrating news and hope you have better luck.
Of interest my flip mirror came with a "made in China" sticker - but the optics seem quite good.
As you would say it would be better if it came with a 48mm filter thread (or maybe we should be thinking if all filters came in 49mm
).
Regards,
David