I don't know what the SVB eggs look like, only the squash bug eggs, unless I am misidentifying them, but you're right, BT doesn't last as long so you're smart to use the Spinosad. Slitting the vine and killing the buggars you would think would kill the plant but I actually slit the stem, pulled it apart to find them and then squished them. Now, if there were more higher up in the stem than I slit it will have been for naught. But it has worked for me. Oh, and the dead plants, the borer was still in the stems of the ones I threw out so make sure you kill them or at the least, put in the trash right away.
Good thing you have plenty of plants even though it hurts to even lose one. Keep us posted!