Careless Driving Charge

So basically I was driving back to my house in a rural area and a cop stopped me to tell me to go around because there was a bike race going on.

Sure enough I didn't have my pants on because it was hot out(jve never done that before) and the cop gave me a careless driving fine for masturbating while driving. Firstly is that careless driving? he never saw me doing anything it was just an assumption. I wasn't driving naked because I wanted to flaunt anything to the public or masturbate infront of anyone althought it may seem that way I did not have any of those gross intentions I honestly just wanted to drive free without wearing anything. I kind of did admit to masturbating to the cop because I was very nervous I didn't want to be on the sex offenders list or anything but before that I told him because it was hot out I didn't really have an excuse he was pressuring me so I said yeah I guess I was but I really wasn't! Is driving naked illegal? will I be able to get my fine erased?

Gee, you really got yourself into a sticky situation there.