Suggestion for small 4 season TT please

The Bigfoot and Oliver trailers both would fit your needs. I owned the largest Bigfoot and it was a wonderful trailer that would heat up and cool down quickly with minimum energy use. The problem is I would not recommend them for full timing and neither does Bigfoot in their owner's manual. They are too tight and do not breathe well. Your body creates moisture and you would have to manage your air circulation within the trailer to prevent moisture problems from within. The way they are built does mean no water intrusion from outside. Bigfoot and Oliver and most likely Escape probably top the list of highest quality, low maintenance trailers you can buy by nature of their designs. They eliminate the largest bugaboo of travel trailers - membrane roof and seams. If you can find one used they represent a low cost of ownership as their resale value will remain high down the road.

Portland has a mild climate. We will hit over 100 this week but that is seldom. There will be days below freezing but nothing that a more porous trailer couldn't handle. Good luck.