I think [name_m]Spencer[/name_m] could work! Maybe it helps that I haven’t heard it on boys very often – I think I’ve only met one – and, as you say, it fits in with the trend for surname-y, masc-leaning names – plus the [name_f]Princess[/name_f] [name_f]Diana[/name_f] connection?
[name_m]Spence[/name_m] if cool too – reminds me of [name_m]Royce[/name_m], [name_m]Scout[/name_m], and [name_m]Kit[/name_m]. [name_f]Penny[/name_f] + [name_f]Pen[/name_f] are cool too