Tonythecarguy (his screen name) had a cooling vest at OHSTOC. This unit pumped ice water from an insulated cooler through tubes in his vest. If said Tee fittings fed tubes in something like a cummerbund or strap on chaps that might be what the doctor ordered.liquid heating is built in....
Now it might be clever the next time you service your radiator hoses to put in a couple of brass tee fittings and create a shunt tube that some how wraps around the vertical part of the handlebars or routs through your seat.. A small butterfly valve could control the amount of heat like the heater control in your car.. If I lived in a colder location I might be temped to do that.