one. what if you DON'T do a barbecue (just thinking outside the box). Barbecuing is time-intensive, and has to be done fresh, except perhaps grilled vegetables (you can grill eggplants and peppers, belgian endive and/or radicchio and zucchine, then marinade them in oil and garlic and pepper, maybe a small pinch of origano and a hint of vinegar for the eggplant, maybe some thyme for the peppers and the zucchine, maybe nothing but salt and pepper for the endive (or put some gorgonzola or other stinky type cheese on top and let it melt). And/or make bruschetta, which can be done in advance. So don't do a barbecue and make food, but eat it outside! Who says eating outside requires barbecuing?
two. You can grill something large - if your grill has a rotisserie, you can do a large piece of lamb or beef or pork. I'm no griller, i can barely light a fire one time in ten and so i never bother. But if you're good at grilling, a nice large roast is really good on the grill. And if you have one of those fancy grills that you can make pizza or bread on, you make a couple of loaves of home made bread the morning of the party, and knock them off their feet with that!
Then make lots of other cold side dishes- rice salad, potato salad, panzanella, and get ottolenghi's Plenty for some incredibly interesting vegetable dishes. Maybe a cold fish dish, or meat salad (boiled beef with lots of parsley and garlic and oil, or chicken salad with celery and carrots and raisins and apple and curry, or vitello tonnato or other. But really, it's not necessary to have a lot of meat dishes if you have one good one and very tasty sides.