AI have been searching for an icing recipe that has a strong marshmallow flavor to use as a filling and and a crumb coat on a fondant cake with a smores theme. The one I am leaning toward is essentially a 7-minute icing. From what I can find, this is essentially the first stage of a SMBC just before adding the butter. My only concern is will this hold up well under MMF? Thank you in advance for any advice!

Google "Marshmallow frosting" and you will find a few recipes that use marshmallows in the recipe.  I found a few that I would like to try.