Using generator exhaust heat

It seems that generator use peaks during the winter.

Why not use more of that heat?

Diesel truck EGR coolers can be had for fairly cheap, they are made from stainless steel, they are designed to exchange heat between large volumes of exhaust and engine coolant.

Put an EGR cooler on the generator, then a auxiliary truck cab heater on the other end connected by heater hose and well insolated, circulate coolant with one of many available 12 volt coolant circulating pumps.

At least 30% of the heat from the fuel that gets burned is blown out the exhaust. What if some of it could be captured and relocated to inside an occupied structure?

Lets say the generator burns .8 gallons per hour of gasoline running it hard charging batteries and running everything else during the generator on free for all. That generator would be using about 100,000 BTUs per hour of fuel. If 30,000 BTUs go out the exhaust and you capture half of that and put it in your structure that would be like having 3 of those small 120 volt space heaters going for the cost of a few amps of 12volt power to turn the pump and run the blower fan.