I am still not clear on why Tier 3, why so many repeaters, why so much data, etc..... maybe scale your system out with one or 2 voice paths and see how the costs break out. Do you really need dozens of voice talkgriups and dozens of data paths available? You will need a Zello ROIP box, MSAT terminal, etc per single voice Talkgroup you are looking to connect to the Zello network.
Also, you have both a technical need AND you are dictating the solution. This is a recipe for ending up dissatisfied with the end product. If you have a list of requirements vs. wants, then sort you needs into a list of priorities. Otherwise, you may be excluding several other viable solutions by demanding Tier 3. TT