Yeah, a 2.5 bar MAP sensor stops at 21.8 psi, since the first bar is atmospheric pressure.
Google searching gives me the impression that Livernois has experience with 3 bar maps for the Mustang ecoboost and there are several direct replacement 3 bar sensors for the Mustang ecoboost, including one made by Motorcraft that is pretty cheap. No idea if that same sensor would drop in to a Maverick.
You could probably talk to Livernois about a 3 bar tune for the Maverick which would take you to 29 psi. I don't know how feasible it will be for them to tune that via email instead of hands-on with your truck for an extended period, but it'll be fun watching you, for sure.