I'm also curious about this and I'm in the process of doing some research. I currently have my unit in North Myrtle Beach listed on Zillow and Trulia, but over the next week, I'd like to get it listed several other places. I just came across this site which looks promising, but I can't speak to it as I literally just found it on the web. https://www.americansnowbird.com/
As far as what to charge, at least in my area I charge less for the winter than the summer but at a monthly rate.
I only deal with long term rentals in the Myrtle Beach area and put 12 months lease as minimal terms yet still get a decent number of inquires from people asking about short term and winter rentals. The listing services I use are Zillow rental manager, Craigslist, Facebook, and cozy. Though I can’t guarantee success, just using these with the winter terms listed in the ad, I would think you would get a decent amount of inquires. So ad these to the Airbnb and FRBO, and you may get what you are looking for. Greg, are you managing your rental in NMB from Ca?