[Rmbodie]

Well, Well, Well , The keys get pretty hot don't they . I would say you might get around 10 mpg . Maybe lower if you use a trailer with a larger surface area than the rear of your Blazer . I frequently pull a trailer with my old one . Just a flat steel deck one for a couple of 4 wheelers . I get 16 with it and about 21 w/out. But I have engine mods other than stock designed for power not economy . If you do not already have a 2 inch receiver hitch . I strongly recomend it over the clamp on type that uhaul will try to rent you . You can buy one and install it yourself for under a $100 .
Real simple to disconnect and with a second set of eyes to guide you reconnection is easy too .
Your hauling weight will not be much of a factor unless you go thru cities instead of interstate . Give alot of extra distance for stopping .
You might even be better off renting a van and pulling your Blazer behind it .Rob