We are also looking for a new 4-season trailer for under $30k. However, we are looking for a lightweight one and one that we can configure and modify to use a Splendide combo W/D.
Open Range trailers are well insulated. In fact, super well insulated but they are also quite pricey. I don't think you are going to find something new in an Open Range model that will fit your criteria ...maybe, but we haven't looked at them lately because we know they are expensive.
We are leaning toward the Northwood Nash which is not as nice or heavy as the Northwood Arctic Fox. From our research and all the reading we've been doing, Northwood seems to meet our quality criteria. We are also looking at a Lance but don't think they have quite the quality for the price as the Nash as they are pretty pricey for what you're getting. You're paying for the lightweight frame and chassis they use.
As far as finding a floor plan that has a separate TV room in the rear, I'm not sure we've ever seen something like that in our roaming around ...but it's not something we'd consider. I think you're going to have a difficult time finding something like that in the under $30k range. But we'll be interested if something like that exists.
Since you're not planning on moving it frequently, have you considered a used park/destination trailer? They larger and if you're full-time living in it, you'll have a bit more room and amenities. They are essentially great big travel trailers that most people will not move around a lot. They are heavy --over 10,000 lbs GVWR-- and need a more hefty truck to tow.
Here's what I'm talking about in the Forest Ridge models but other manufacturers make them too ...some are well insulated as they are designed to be lived in for longer periods of time:
Destination Trailers - Park Trailers by Forest River
I hope you get some good suggestions in this thread as we will be following it too.