I say [name]DASH[/name]-uhl (am in UK). The only other name I can think of/find which could work with [name]Dash[/name] is a japanese name Tadashi. You may get away with these though: [name]Dallas[/name], [name]Darius[/name], [name]Davis[/name], [name]Dawson[/name], Adesh and Aldrish.
I have a nephew named [name]Dashiell[/name], and they pronounce it [name]Dash[/name]-ull. People who aren’t familiar with the name usually pronounce it the way you do, but I believe [name]Dash[/name]-ull is the ‘correct’ way.