Definitely looking forward to an update!!
Still working on the 550 here. I should have just bought an acrylic tank. I'm not sure I've saved money, to be honest. Yeah, my biggest concern right now is heating and overflow drain.
So the idea, is that the sump will overflow into another tank via a bulkhead. There was a video on youtube, I have to look for it, where a guy plumbed the overflow into his return piping... I cannot recall how. I want to find that video and do that. But yeah, overflow into another tank and pump out to the washer drain--to the sceptic tank. My current overflow on my 200gal drains to that drain and I've never had a problem. Maybe its a temp fix until I can figure a drain system outside an exterior wall. I'm just afraid of the pipe freezing and water backing up into my basement.