does your distro have three 0awg in?
you can do it and it will work, just properly size the fuses for 4awg, so between 125-150A depending on the quality of 4awg.
i would have 0 awg from the front battery to the rear battery, fused on both ends. then 0 awg from the rear battery to the distro block, fused at the rear battery. then out of the distro into the large amp with 0 awg, and out of the distro with fused 4 awg to the other amp.
you should have a volt meter at the dash that monitors the rear battery voltage.