Never baled hay. Spent lots of time on a JD 520 with a rear exhaust pulling a four row cultivator. The muffler was laid flat just below the level of the hood on the right hand side of the tractor with the exhaust curved down to run along the frame and out under the rear axle. The row marker was also mounted on that side so I was always leaning that way. The heat from the muffler came right back at your face. But the hottest was hoeing cotton in July. We would get one of those little 5 minute showers, just enough to dampen the top layer of soil and then back to the field. Just enough rain to drive the humidity into the 90% range with a 90+ degree air temp. Old fellow that used to work for us wore a long sleeve shirt and bib overalls in that heat. He didn't seem to sweat much. Don't know what his secret was.