Yeah, they'd be easy to convert. But honestly, they're pretty weak and I'm not sure it'd be worthwhile.
Feeding Dependency is only 1 Refresh, so even if the Tattoos gave you perfect hunger control they'd need other substantial upsides to be worthwhile. And they don't.
A little while ago I toyed with the idea of Tattoos for people who use Sponsor Debt to represent the need to feed. My idea was that they could let you resist a Compel for free once a session, or let you shed Sponsor Debt when refusing a Compel as though you had accepted it.