I love this idea bro!
Not only is it really low hanging fruit, but it's also standard practice in a ton of mobile games.
While the revenue estimate at the current time doesn't seem to be that huge, it's still easy money to start pulling in for the team. And there's the scalability factor you mentioned, that will start getting juicy, the more new players start flowing into the game (possibly next crypto bullrun?).
And I love that's it's an optional, non-intrusive form of advertising, as banner ads would start making the game interface look yucky (I'm a graphic designer, so that would be poison for my eyes 😂). The only thing I would be down for in regards to banners, is SPL guilds being able to pay for ad space to recruit for their guild, for instance, as that would be an ad that still feels coherent to the SPL theme.
But to get back to your idea of implementing RVAs...if the team isn't down, we might have to force the initiative with a proposal. If they don't know what would be best for them, we'll show them ;)