The stock-receiver gap is filled by the plastic spacer they provide, the other attachment points go in the slot about halfway back in the body of the stock.
They are both great, I just liked the larger window. The RMR might be more durable, but the SRO isn't a delicate flower. For my use (110% recreation and home defense), it shouldn't be an issue.
I'll open it after dinner, otherwise I won't be at dinner.
I was hoping Santa might bring my Illinois FOID soon so I can send my gun to @StrangerDanger.
But I can't complain. Merry Christmas to everyone, and Happy New Year.