The proof-of-work would be switched to the signature of our private key and we would set up a server to produce one block every 2 minutes.

I have a concern on the security issue. With such approach applied, the cornerstone of a digital currency might be compromised. PTS is in essence a P2P payment network, which is backed by the proof-of-work mechanism with enormous decentralized computational power, be it Amazon clusters, bot-networks or anything else. That's how the system works. You shouldn't simply degrade the conventional mining procedures — even if they generate large billings — since your centralized replacement could not offer the key merit. I understand your intention, but this may not be a clever move.