I thought there would be a problem, so it’s SMD only.
I was doing a tutorial and playing with ground fill - I’m not a FZ superuser - and I got it to work, but then I remembered plated holes. You set a seed on one net, set top layer, and ground fill that. Then deselect that seed and seed the other net, select bottom, and ground fill that. I now have a 5V top copper plane and a GND bottom plane. I wonder if you can put a copper blocker right across the bottom of the PCB so it’s split in two, and use the seed, fill, swap seed, fill, etc, so that you get 3 separate planes, ie, 2 GND planes and a PWR plane. 
