A 65 pint dehuey would handle that shit with ease, bro................obviously depends more on the plant matter than the wattage, but yeah, 65 is plenty for that (IMO), unless you live in the Amazon.
As far as the direct drain option - mine has it, but it's *not* as big of a deal as you'd think - assuming the tank is accessible, they're all made out of plastic - i.e., pretty easy to take a step drill bit and set up your own auto-drain by hooking up some hose/tube fittings to it.
And if you can do something with that dehuey waste water, that's even better...........I have mine set to top-off my veg reservoir (comes out at ~5PPMs from the dehuey).
EDIT: Shady, not sure if you have an atmospheric controller or not, but if you do (or ever plan on upgrading to one), make sure to get a dehuey with an "auto-restart" option (generally will have the analog knobs and not be a digital, but not always).