here's a picture of three hammocks under two overlapped tarps.
you have the skills to make a hammock tent for two w/ no prob.
you would just make it wider (maybe 14"?) & sew on the walls that form the sides.
but the ends would get a little complicated w/ two sets of hammock supports.
but i don't believe you would really need to close in the ends in most cases.
you could rig something... it just wouldn't be as nice & neat as the rest