There's no way a leaking a/c can contaminate the oil….
When the air is hot and humid it's not unusual to have water condensing on the cold portions of the a/c system…
The only time I had problems with a very hot dipstick was with my '95 E-350 with the 5.8 engine. I was hauling 'just in time' auto parts (put on 280,000 miles in 18 months) and I was using the local fleet store's house brand oil made by Citgo. It seemed to be the culprit as I changed to Mobil 1 and never had any problems with high oil temps after that.
I'm not saying the oil is your problem… just giving you my input.