I don't think there is any alternative which works well in hot weather. Many have said that the alternatives have asphalt in them which gets too soft in hot weather.
Here is a link to a product which claims it smells less, yet still surely would get soft and nasty in the heat. GTMAT Automotive Sound Deadener Dampening Dynamat/Fatmat Alternative
Peel and Seal from home improvement stores is most commonly used, as it is cheap, yet also contains asphalt.
My suggestion> Change your exhaust system back to something slightly quieter.