Hi @Holly43. It's possible to get insurance for your rental property, and I'd recommend it over trying to sneak it past your current insurance company. Because if you have a claim involving a guest, that guest will be contacted and probably won't want to provide false information to an insurance investigator. Which means your insurer will find out you're an Airbnb property soon enough. Besides, it's always best to do things on the up-and-up.
Try these guys http://www.peers.org/product/homesharing-liability-insurance/
These guys offer policies underwritten by Lloyd's of London. http://www.proper.insure/
In addition, I read in an article that Chubb offers short-term rental to its homeowner's insurance policy holders.
Our Airbnb hosting experience was actually delayed by about 18 months because our homeowners insurance company, AMICA (an otherwise great company, BTW), told us they wouldn't renew our policy if we decided to start renting our guest house out. They said this constituted a commercial enterprise and they don't write commercial policies.
Since then, AMICA has evolved and now offers short-term rental coverage under certain circumstances -- namely if the rental space is separate from the main dwelling and guests have their own entrance. (This reduces the risk of theft and fire to the main dwelling.) It's a rider to our existing policy that costs us about $15 a month.
A local insurance broker -- someone who represents multiple insurers -- might be able to hook you up with an insurance company operating in your market. We spoke with one this summer who explained that based on his experience, the complicating factor is if you serve food, as that opens the possibility for other risks such as food poisoning. But that wasn't a factor in the coverage we secured through AMICA.
Finally, if you just Google "short term rental insurance Colorado" you're bound to be pointed to at least a few other options.
Good luck!
Carl and Diane