Roasting vs Crockpot

I marinated a pork leg roast in mojo sauce, citrus juices, garlic, basil, and other Latin spices. The recipe wants me to roast it in the oven for nearly 6 hours but I don't want to run my oven for that long on a hot day. I understand I won't get a crust on my roast if I don't put it in the oven . Can I sear it first or cook it the oven the last 30 mins at a high temp to recover the crust if I DO cook it on the crockpot? Any suggestions from going from roasting to a crockpot?