Prior to building this, talk to 10 storage company owners and confirm that they're both amenable to you signing up customers for them and that they will pay $40

Prior to building this, talk to 10 storage company owners and confirm that they're both amenable to you signing up customers for them and that they will pay $400+ for that. You may find some who require a credit check, which they may or may not be happy about you doing, for example.