Looks like it's just you & me kid!

When I have to take a salad to a BBQ, being vegetarian I take one that I'll like & will be filling for me! I usually do roasted vegies the night before or that morning, ie: sweet potato, pumpkin, red capsicum, eggplant, zucchini, red onion - or some variation of those. Then I put it on a bed of cous cous. Sometimes for that added protein I'll put some chickpeas in it &/or pinenuts.
As for dressing, I'll make my own with olive oil & balsamic & a bit of seedy mustard & sometimes honey. It's also nice with natural yoghurt too.

If this is too much effort, how about some kind of bean salad, with mixed beans from a can & chop up vegies like capsicum, celery, spring onions or whatever...that is if you don't mind blowing the doona off that night!!