Hi John
I can’t talk to the weight of the scope as I have the RC8 but I use the moonlight focuser and I can happily hang an MMOAG with an STL6303e plus filter wheel for 8 2” filters. It will have no problem with the imaging train you are thinking about. It will hold focus pretty much all night with the CF Tube.
I also have the ASI1600, OAG and ZWO filter wheel. Again, no issue with that configuration.
I don’t use a flattener and with the smaller chip it’s not needed.
Ron at Moonlite will help with accessories but would suggest threaded connections wherever possible. He has a few options there as well
PS: just read Paul’s comments. My experience is my experience with a CF tube RC8. Others may have different ones
Cheers