It's the voltage that determines the current for a power level. DC actually works favorably here.

My idea was to disconnect one of the services to avoid having to pay for the service charge twice. Not go off grid, but just a potential "low hanging fruit" to pick.

Two things come to mind regarding the diesel. You may be able to purchase your fuel without the highway tax. This seems to vary by state but the difference could save you about 30%. The other variable is who you get your power from. When I lived in eastern Oregon my electricity rate was more than double that of the Willamette Valley.

If your electricity costs are high and you can get fuel without the highway tax then the generator becomes a viable option, certainly cheaper than batteries. And as was mentioned above, the recovered heat from the generator can help offset its cost.

I have no idea what a dedicated UPS for your data center would cost. You will still need something to carry the data center load long enough for the generator to come online.

Go for ductless AC to avoid cooling problems in our data center in summers.