Geeting from the Florida Panhandle
Welcome to the Forums. We're glad to have you with us.
As to your question, I don't think that a full size blazer is too big to tow a 31' Airstream. Anything smaller may not be sufficient.
The Blazer is a fairly short wheel base vehicle. As such, I would want a quality weight distribution hitch system. You don't want the Bronco's steering to become adversely impacted by lack of weigh on the front axle.
You will also need to make sure that your Bronco is properly wired for a tandem axle trailer with electric brakes. You will also need a trailer brake controller installed on you tow vehicle.
SuEllyn & Brian McCabe
WBCCI #3628 -- AIR #14872 -- TAC #FL-7
2015 FC 25' FB (Lucy) with HAHA
2005 Suburban 2500 Quadrasteer (Olivia) & 2011 Silverado 3500 (Fred) with Outfitter Truck Camper (Ethel)