SMPlayer runs mpv with the --no-config option to prevent interferences with options from the mpv config files. Maybe (untested) if you add --config=yes to preferences -> advanced -> mplayer/mpv -> options then mpv will use its config files.
I have tested that and the answer is no that doesn't work. It doesn't throw a error but it doesn't do anything using you suggestion. Is their a way you could maybe add that in a future version where smplayer can load just from the mpv config and no extra options but what specified in there The profiles options are a nice addition for quick changing of options for different media. And you can set them to occur in certain situations for certain media.I know its kind of counter productive when your trying to make them easier for people to use but for power users it allows custom configs.