Hi, I haven't been on here in ages, but just checked in and saw your post. If it's not too late, I have 2 cents to add.
I prefer not to use chafers on buffets unless it's an outside event and it's cold out.
If I need them, I often use wire baskets to hold platters (metal, in the case of your mixed grill), or make chaferless chafers using glass blocks or bricks to hold the pans with the sterno underneath. Another catering friend has used white rectangular vases to hold white cookie sheets with the platters on top and sterno under for a modern look.
If the weather is warm, I simply use platters and replace/refill directly from the grill. I like this look better than chafers. It also saves on bringing lots of bulky items on a job.
If you've already done your event, what did you use?