Marinade I used to make Char Siu:
1/4 c sugar
3 T sherry
2 t soy sauce
1/3 c Hoisin Sauce
1 t minced ginger
1/4 t five-spice powder
1 t salt or less
1/4 t red food coloring
Mix all and marinate 2-3 pounds pork strips. I use a Boston Butt cut into strips. Let marinate overnight. Place on a cooling rack in a sheet pan. Pour some water in the bottom of the pan to keep the meat moist while baking. Bake at 350* for 20 minutes, turn over, bake another 20 mintues. Put the oven on broil for a few minutes to char the meat. Don't burn it. I just love this stuff. I add it to my Pork Lo Mein.
I used to make Char Siu from scratch and it turned out fine, but slowly I prefer just to use prepared sauce, and it turns out just as good. Of course, I add a few things to prepared sauce like honey and sesame oil..etc, but it is much easier.
I hook the meat inside the oven and put a pan of water underneath. As for the bake time and temperature, they vary. I used to go for the like higher temperature like you did, but have been using the lower temperature and longer time. Yes, I also broil for 1-2 minute to finish off.