Mine tends to get dirtier parked than traveling since we're mostly fair weather campers, so I usually wash before a trip. I like to start with a clean trailer. A small amount of car wash soap in lots of water, nothing fancy. After a recent trip I did clean off quite a few bugs from the front when I parked it for storage. I used baby wipes (which also works when you're in a campground and need a little touch-up).
The biggie is wax, which I do twice a year, spring and fall
. It's a workout, even on my 13'er (and a good antidote for 3'-itis). I use an automotive paste wax. I keep thinking I will give the 3M Marine products a try (recommended by quite a few folks here), but haven't gotten around to ordering them. Until and unless I do, as Donna says, anything is better than nothing!
I envy you your brand-new gloss, but, as mine had already acquired a patina when I bought it, I don't have to sweat the small stuff, like the time a scrap of tire kicked up on the freeway and left a long, black lash on the front corner.
Bar Keepers Friend mixed with water into a runny paste took it off.
If you value that gloss, covered storage is the best thing you can do, of course, and a high-quality cover (i.e., Calmark, $$) next best. Avoid cheap knock-offs- they don't last and poorly finished undersides can do more harm than good. If blowing dust is common in your area (as in mine) skip the cover, as dirt will get underneath and turn it into sandpaper.