Hi Grendal,
I use Z-Poxy a lot and once a good smooth finish has been attained I always prime it with any of the 3 Halfords primers available. While they are acrylic as opposed to cellulose, they do have a carrier solvent in them but it seems to be OK if built up in very light spray coats.
I would prime the whole hull in their white and when dry, mask off and spray my topcoat white. Leave plenty of drying time before using a low-tack masking tape, I use Tamiya and Frogtape, the latter from B & Q or Screwfix Direct.Tape and newspaper cover over the white and respray your lower colours. Halfords Red Oxide primer looks pretty good as an anti fouling colour but other colours work just as well. I also try to mask and spray any boot-topping at this stage rather than use trim tape, a little trick here is to lightly spray clear matt varnish over the thin tapes for the trim before adding the colour, any creeping should be minimal and clear anyway.
Most paints go well over Z-Poxy and Halfords except Cellulose (a No No!!) Try to do it in a Not Too Cold area if you can, in this weather that can be hard to do.
Cheers....Ron Rees.