Good memory Yulli
I did indeed buy it used and NOOOOOO don't use the stupid small fan. Go for the big one. Its the biggest disappointment in my trailer and one which I plan to remedy when I save enough money and courage to cut a hole in the roof.
Hmmm other changes... depends on cash haha. I would recommend buying everything you want initially if you can afford it instead of retrofitting. Nothing is more painful than watching someone cut up your baby. Also its usually more expensive in the long run.
Make sure you get the pneumatic front wheel. Its expensive but the medical bills from putting out your back pulling will be more i promise
Get a solar system of some sort. It doesnt need to be theirs (I use two goal zero boulder 30s and their solar charger) but if you plan to stop for more than one night youll want it
Fridge and slide go without saying. Once again expensive but worth it.
Youll want the fuel cans. I havent had to use mine yet but I was darn close one time when I had long stretches of deep sand. If I hadn't had the extra 5 gallons I would have been REALLY nervous.
Skip their awning and go with an ARB. I used an Eezi Awn bag awning and for an awning I loved it, but if your wife is like my girlfriend youll want more camp and change space. We just picked up an arb awning with floored room. Dog will sleep in there, it gives us a changing and relaxtion space with privacy out of the sun or rain or snow/ it keeps bugs out. Other major bonus? Cold weather camping becomes easily doable. Combine with this
http://www.amazon.com/Camco-58031-Campfire-Portable-Propane/dp/B000O51VJ0 inside the room and you have a fully heated space with heat flowing into the trailer as well. Turn it off at night and enjoy the warmth the trailer maintains.
Im sure there is more but I cant think of it all at the moment