good thinking on those bandannas. i always try to let our customers know to "remember" the lowly tech who is crunched inside a tight LT spot trying to repair their problems suggesting a cooler shady "safe" area or out of the way spot to work. Of course this is not always possible. Another thought to make clients more aware: Have added to your invoices "Thanks for helping our techs stay safe at your your place"
Of course our vans should also have AC inside to cool down between trips.