You could post them as 'riderless horses' on either craigslist or an actual horse site. People who are looking to ride wont mind the cold. The barn I ride for now...thats how I found them. They were looking for someone who wanted to ride as they have too many horses and not enough riders. Over 60 people wrote to them looking to ride. They picked through the weirdos and came up with me...lol!
Its just that simple though. You are going to have to continue to pay the bills...the only thing you don't really have time for is riding. When I was considering leasing out my QH before I decided to just sell him, I wrote up an agreement making his rider liable for his condition during a ride. They were also financially responsible for all the 'extras' like if they wanted to trail ride excessivly...that was fine but someone had to pay for shoes...and since I would only be riding a few days a week...it wasn't going to be me. If they wanted to show, I needed noticed and they would have to pay for coggins, transportation and entry fees. I posted it as a free lease and had a few people interested...I just didn't like any of them!