Water Line Sizing

I am considering purchasing an inactive 160 space mobile home park and will need to drill a new well and install new PVC waterlines to service the lots. I am being told that I need 1.5 gpm per lot and there are 4 rows of lots; 2 of which are back to back and am planning for those 80 lots to be serviced by one waterline. Everything I read here says 1.5" lines but when I go online to Pressure Loss Calculator For PVC pipe and input Sch40 2" with 60 gpm and 2400 feet of flowline; I get a ft/sec Velocity of 5.7297. And a warning that Ft/sec Velocity of over 5 should be avoided.

Using this calculator is shows that I need to install 2 1/2 for the 40 lot rows and 3" for the 80 lots run with a 4" Header connecting all 3 lines.

2 questions; since this is an irrigation website, am I overbuilding the lines and increasing my costs with this set-up OR is a number wrong in my formula, ie not needing 1.5 gpm per space?