They could bring in just about any provider under the extremely broad "services near children" provision. Once inside, they could give them a choice - be charged and probably win, but still have to deal with the wasted time, court fees, etc. Or, hand over your cell phone for 15 minutes and then walk out the door. Once armed with the numbers and text messages, LE could send out a general "Please be aware that this number has been found in association with suspected procurement of sexual services, which are now illegal..." text. They could also share the numbers with other agencies, so that the next time you try to cross the border you're denied entry due to a possible prostitution connection. CBC did some stories recently about how just about any interaction with LE goes on file, and can come back to haunt you years later at border crossings, government job hirings, etc.
None of this would cost much in the way of time or money, but would throw a big chill into the "hobbyist" community.