PC socket and hot shoe together, Yes (including hot shoe extension cable of course). PC socket is manual flash mode only.
PC socket and internal flash, No. PC socket is disabled if internal flash door is open. I think the point is that this also rules out Commander and PC socket.
But also (and seems better, fewer cables), the monolight is manual flash mode of course. Both units (monolight and SB-700 SU-4 mode) have internal slave sensors which will be triggered in sync by the flash of another manual flash. So PC cable to one of them, and its manual mode flash triggers the other slave flash in manual mode. Should work really well.
Not all speedlights have a slave or PC connector. SB-700 has SU-4 mode slave, but does not have a PC connection, but hot shoe cable in Manual flash mode would still work (slave mode requires Manual flash mode).
The hot shoe extension cord length limits distance to an umbrella right beside the camera (which is where the fill light ought to be anyway). But the cord coil tension tends to tip over light stands if further.