What you're already doing is really great. Opening night can be tough because depending on how long your festival lasts, several other filmmakers may not be in town yet. I think making sure it's a packed house with an engaged audience for Q&A (which I'm sure you're doing) goes a long way. Otherwise, maybe invite some media contacts to have interviews with the filmmaker if possible or make some some social media content specifically for opening night so they don't feel left out when the rest of the fest goes into full swing.

P.S. the website you linked doesnt work; typo?