Hi, 26 miles is not a long distance when working with fiber. I would have just one active POPs (or two for redundancy). Use DWDM to expand your 6 strands into as many links as you need. You could also use GPON with splitters, although that will only deliver 1 Gbps (on a shared 2.4 Gbps) at this time.
DWDM allows you to sell "colored links" to customers, that they can do anything with. MPLS might be overdoing it or not, depending on your background and experience. Using VLANs or layer 3 routing might get you the same thing. I would say the proposed network is small enough that you could get away with just about anything. Just remember that you need to protect your network from customers. Eg. you are using STP and the customer enables STP, you could very well end up with a disaster if not careful. Many network protocols have zero security and many switch configurations are vulnerable to simple mistakes by default. Regards, Baldur