Welcome to the Trailmanor family!
I am relatively new as well, having bought one just over a year ago. Unlike yourselves, I did not come from a previous trailer, but I know the feeling about storage. We got ours because I could legally keep it in our driveway, it had a full piece washroom, and it would sleep all four of us. The help I saw on this forum also played a big role in my decision. After perusing all the posts, I realized that I could pretty much fix anything.
There is pretty good storage if you are creative, but it does come with a cost. It requires more time for set up and breakdown as you have to stow things away. It also add a lot of weight. The trailer itself is light, but the design of the trailer puts more weight on the hitch. For such a light trailer, it is really easy to overload your rear axle of your TV. I thought it was just my inexperience, but then a really experienced TM owner, Bill, who is extremely knowledgeable, shared his TV and trailer weights here:
http://www.trailmanorowners.com/foru...ad.php?t=19179
Lots of good information here:
http://www.trailmanorowners.com/foru...ead.php?t=9655
Back to storage, though. You have the slide lounge, so this is how I'd look at storage:
1) Nothing can go above the height of the lower box. I always take a last look around the ceiling and walls to make sure nothing is left up. I believe the beds can accommodate about 1" of material. This could be your mattress topper. At least one owner redesigned his latches so that he could keep a 2" or 3" topper on his mattress. I'm not sure how well that has worked in the long run, but if you have the original corner latches, they will likely need replacement.
2) Nothing can go where the slide goes, but you can store things on the slide up to the height of the lower walls.
3) Store anything you might want on the road in your TV. It is a pain to open it up just to get a chocolate bar. If you have to stop on a hill, you may not be able to open it. Or you'd have to unhitch the trailer to level it first, which is probably illegal just about anywhere on a public road. We have opened it up several times in a parking lot to use the washroom or store food we bought at a supermarket.
One last thought. You have the trial membership, so remember that when your trial expires after 30 days you won't have access to many of the useful sections on this forum. Of all the forums I have ever joined, this is the only one I pay for. BTW, Chris (who handles the membership) didn't pay me to say this!