I have MS.
Unfortunately everything costs money.
20 some years ago I used an ice vest. My torso was cool (too cool?) and everywhere else was hot.
I tried the evaporation vest, but we get HIGH humidity here, and I ended up feeling like the evaporation stuff was holding heat IN, not getting rid of it, especially the evaporation skull cap.
While wearing the ice vest I fantasized about a portable air conditioner for riding!
Then I discovered the technical cooling fabrics. Right now I wear:
A FITS technical fabric shirt, long sleeves, with mesh on the sides. Keeping the sun off my arms really helped me feel cooler.
The Kerrits IceFill tights with a silicone full seat. This does not cool quite as well as the Kerrits Flow Rise Performance tight, but I was slipping all over the saddle with the Flow Rise tights MUCH MORE than with the IceFill tights. I LOVE silicon full seat tights/breeches! Since I am more secure in the saddle I do not waste as much energy just trying to keep my seat in the saddle and I end up less tired after riding.
Moxie ventilated half chaps–My saddler said Moxie does not make them any more, but that Smith-Worthington also sells ventilated half chaps.
The Columbia Sportswear Freeze Zero Neck Gaiter–I pull this up over my head (under the helmet) and it really helps wicking the sweat away from my scalp. It cools better when I take the helmet off, especially in a breeze, but it is amazing how much sweat it picks up. It ends up a lot wetter from sweat than my hair does.
A terry cloth head band.
Wicking socks.
Staying out of the sun as much as possible. I also ride early in the morning during the hot season, 8:00 AM. It is more humid at that hour but the sun is not as high and the ground has not heated up yet. I also ride just 30 minutes before I am too wiped out to continue.
I also do better in an inside riding ring, unfortunately I cannot afford to take lessons at a barn with an indoor.
I still get hot and sweaty, but I am a lot better off than I was before I bought all the technical fabric riding clothes!