can I BBQ/smoke veggie brats?

You can grill veggie brats, yes. However, since they're not made with meat, you shouldn't cook them as long as the ribs. Doing so will burn them so much, they won't be edible. Check the directions on the brat package to see how long to grill them. Also, meat-freers prefer their foods NOT to be cooked where meat has already been, so remember to clean your grill very well and have the brats and ribs in separate places on the grill or, since the cooking times will be different, clean your grill, cook the brats, set them aside, then grill the ribs. It seems trivial, I know, but it'll mean a lot to your veg friends and they'll thank you heaps!!!

make sure you don't use gas to heat the brats because gas comes from crude oil which comes from prehistoric animals.