Like for any chicken-and-egg problem, the first step is likely is to reduce the size of the market for working out a solution. We need to have find a small market where businesses would accept a SLA from a side project, a way for side project builders to offer SLA and adhere to it.
As for what that SLA should be, We need to discuss more about the requirements, challenges faced by both the parties. Hopefully, we'll find that out here.