Any ideas for formal names for either [name_u]Cade[/name_u] or [name_m]Cabe[/name_m]? I have:
[name_m]Caden[/name_m] (not a big fan)
[name_m]McCabe[/name_m]/McCade
Kincade (probably my favorite, but it may be too weird to actually use)
[name_m]Caleb[/name_m]
[name_m]Arkady[/name_m]
[name_f]Cadence[/name_f]
[name_m]Cadogan[/name_m]
Cadet or [name_m]Cabot[/name_m]. Prefer [name_m]Caleb[/name_m] out of the names on your list 
Cadriel, [name_m]Cabel[/name_m], [name_m]Cadell/name_m
Here’s a strange one… Cabeswater. That’s the only one I can think of.
I would just use [name_u]Cade[/name_u].
You could potentially use the initials K.D. or K.B. to get to those nicknames.