You're right: infact monoply pickguards are often hard to find alternatives to...
Something very close to it it's the Squier Classic Vibe '50s one. I got the Lake Placid Blue (basswood body) one, and it sports monoply white pickguard just like yours, but if ask for the present ButterScotch version (pine body) it sports a black pickguard.
I once had a Mike Dirnt Precision and, as enlisting a '59 splitcoil pickup, it also adopted (sorry: it adopts) a three ply white/black/white pickguard
Black one on Precision 60th Anniversary, but again with a splitcoil pickup, so I dunno if the spacin' is singlecoil wise
No: the only alternative comin' to my mind is Squier Classic Vibe '50s ButterScotch (black) pickguard
l'innocenza e l'intelligenza nel miracolo della Creazione.