I was out of town Sunday, sorry. Anyways, I thought you were running two drivers in a 8ft3 enclosure. Looks like running one driver in each 8ft3 box running off one channel of the XLS 1500 will work. Excursion is in check.
And no, you don't need a hpf because the XLS Drivecore amp line has a built in 20hz hpf.