evaporative cooling gear to be worn on top of riding gear?

[bluesman]

Gentleman,
Need a word of advice and experience and any info.
For years I was coping with "too hot + traffic" by just...whining about it and carrying on.
As I getting old....sorry "mature" I realized that there must be smarter way about it.

So, here is the deal. I know that cooling vests available for wearing under gear.
I know principle of operation.
Question is - what if I want something, that worn OVER gear I ride in and cooling it instead of cooling body directly?
And - something to may be put on the seat or over pants to cool...ahm...bottom part of body?
Any experience with any cooling vests etc. will be highly appreciated. I realize there may be no ready solution, but I will appreciate any bit of information - for example about how effective those vests are etc.