One of the requirements was SILENT. The Bessa's aren't that much quieter than what you already have. They're a vertical travel shutter and ain't quiet.
Leica is ruled out for budgetary reasons. (1.4 lens) I believe the only fixed lens RF was the Yashica Lynx. leaf shutter, so no noise.
A screw mount RF like Canon would give you quiet and a 1.4 lens is around $400-$500. the finders, like the older Leicas are kinda squinty though. You could use an accessory finder, focus once and compose with the finder.