Hi there,
My Fiance does roasts in our BBQ all the time, he heats it up to about 180 degrees with the hood on, puts the roast on a foil tray, you can buy from the supermarket (that way you can throw it away & save on dishes ) & puts it straight in, no turning or anything -if you wanted to season it you would do that normally before putting it in but we do pork without any seasonings cept salt & its SENSATIONAL!!! We dont cover the pork but we always cover other meats otherwise it can be a little dry. Roasting it that way gives it such a great flavour, much better than in the oven & you can do your vege's that way aswell, but not at the same time ofcourse.
YUMMO!! I'm inspired now, we'll be having a roast on the weekend!
Enjoy your roast however you do it