I did variations of this in the early 80's. First I ran my modified Fender Bassman into a dummy load I built, used a line out which was a signal padded down from the speaker out, and ran that into an EQ and SS power amp. Worked fine, but I wanted more.
So into my Bassman, I wired in a preamp out, and power amp in. I had a Peavey MK III and had wired in an adjustable aux in.
I ran the preamp of the Bassman into the Aux in on the PV. (The EQ also worked on the Aux)
I used the crossover in the PV, ran the high out to the power amp of the Bassman into 10" speakers (crossed at 300-500Hz) and ran the low end into the PV power amp (driving 15's and later 18's.)
Worked great. Oh for the great bi-amped days of the 80's.
Man, I bet that sounded fantastic. Your crossover point there is pretty much where I end up when messing with playing bass woofers and guitar speakers together.
