Add on Screen rooms
I don't know about other brands, but I have a CareFree screen room enclosure for my trailer (a 23 foot Wilderness). We used it at a campground for the first time this summer. One trip , we had my brother-in-law and his family with us, the other we set the trailer up for 2 weeks and used it as a "cabin at the lake". It took abut 15 or 20 minutes to set up and take down, worked very well at doing what it is meant to and stows easily. We heard a lot of comments from other campers, a few even thought about getting one for themselves. Having used this extra space, I can say that I would not want to be without it on any trailer we may buy in the future.
Since it came with the trailer , I don't know what the initial installation was like, but it looks like the first time was a pain with all the fasteners to line up, etc., but well worth the effort. As with any such project, plan on having plenty of time and READ THE INSTRUCTIONS twice before beginning.
If my experience is any indicator, you will be able to almost double your living space without adding more than 75 or 100 pounds to the travel weight of the trailer. Have fun and enjoy your little big vacation home!