I think it's fundamentally counter productive to hide promotional teaser images behind exclusive tiers. It's another flaw in the Patreon economy, higher tiers need more rewards, and that can create weird situations. Promotional items should be shared by the dev everywhere. But what do you give patrons that give $40/month? Polls? Do you let them request bonus scenes?
When I ponder the idea of my own game, and I think about tiers, I wonder if it wouldn't be better to have just a single tier. Something like $15 gets you everything. If you want to donate more because you love the game, awesome, but you don't get additional benefits. I don't know if there's a good answer, but L&P's approach seems counter productive.