it will be enough.. can add heat lamp that also comes with the exhaust over the toilet. You can also use heated towel racks that serve to heat the towels and are also another source of heat.

You will have plenty of heat!!!

We have a basement bath that has electric radiant (with its own thermostat) under the floor tile, and a Panasonic heat/vent unit in the ceiling. The floor heat keeps it warm for normal use, and the Panasonic heater gets it really toasty for taking showers. Its a very effective combination. You are probably required by local code to have a vent fan, so turning it into a vent/heat combination is a minor step up.

Bruce

What is the proposed power source for these heaters electrical resistance, or hydronic from natural gas, geothermal thermonuclear,...?