I'm with you on the wet towel thing. I'm sure it doesn't actually make a big difference in the body temp but it sure does make it more tolerable somehow or another. I use that and a huge wide brimmed straw hat, white shirt and sun glasses. Makes it seem cooler anyway.
The neck wrap does make a big difference. This is the first time I used ice but I use to make up a kepi out of a wet towel to hang over my neck. I would wet and then fold up a small towel so that a bunch of it would be sitting under a hat. A long part of the towel would hang over my neck. Your neck has quite a few blood vessels if you keep them cool you can work in the heat. If the neck and/or head heats up you are done working for awhile and if you don't get cooled off, well one could simply be done.
I learned the wet towel trick over the back of the neck when I was a teenager digging a trench next to a pool in south FLA in the summer time. I would overheat and cool down under the pool shower. I had a towel, thought of the French Foreign Legion kepi's and made my own on the spot. lol
A few years ago I had a bit of trimming to do around the house. Something I could do with hand tools. In the short period of time it took me to trim the edgers around the house I was done. Very over heated and very out of breath. I was bent over which exposed my neck to the sun. I did not think the short amount of time the job was going to take required the kepi towel so I did not fold one up. I should have because I was DONE in a short period of time.
I spent six hours behind the DR yesterday. I have never been able to handle more than three hours partly due to back injuries that seemed to have healed! Woo Hoo!

The ice on the back of the neck really made a difference. It was the first time I have tried it and it worked. I could feel the coolness and I know that helped. If I had been wearing a hat that would have helped as well but a hat gets in the way of the ear protection radio.
Without the wet towel kepi and the ice pack there is no way I could have worked those six hours. After the end of the six hours my muscles were gone which was good because the mowing was done and the DR was sputtering on the last bit of gas.

I am feeling it this morning but not too bad at all. I figured I walked 6-12 miles behind the DR yesterday and the DR will work your back and arm muscles something fierce. It is going to be 102 today with a big drop in temperatures over the next couple of days.
Later, Dan