We needed some extra room on our last trip so we got a cargo carrier basket that hooks into the hitch on our Trailblazer, it worked great for us. Still had the extra room but wasn't towing anything. We had a lot of stuff too!!!! This is what we used
http://www.discountramps.com/hitch-cargo-basket.htm We really loaded it up, and dh put a tarp around it from the bottom up so we didn't get any road spray or rain and put a 4 ratchet straps, it went no where!!! We purchased ours at Harbor Freight for 59.99, its aluminum.