I'm also with State Farm and have insured our TT with them. I did an online search and got a few quotes from other insurance companies and all were $200+ more expensive. I have a separate towing/roadside assistance through AAA though.
We have Geico specialized RV insurance. it covers replacement cost and contents. It is much better than "automotive" insurance which isn't that good. Good Sam and some other companies do offer specialized RV insurance. I strongly recommend specialized RV insurance because of the nature of RVs vs. cars.
2004 Chevrolet Silverado 3500 LT with a 2004 Jayco JayFlight 29BHS
2014 Greyhawk 31FS with a 2007 Tahoe toad
2014 Thor Palazzo 33.3 with a 2007 Tahoe toad
In a trailers case I don't think you can split the policies with liability coverage. Your TV and TT should be the same provider in a trailers case. Motor home would be a different deal.
Make sure you are getting a specific plan that covers your unit when detached from the TV. Some policies may be written as a rider on the TV and once you unhook you are not covered. I also have Geico and new model year replacement with a roadside assistance plan specific to the trailer and TV.
2014 375 BHFS Eagle Premier
2014 Ram 3500 Longhorn DRW CC
6.7 CTD, Aisin, 4.10's
Talking insurance can be like talking motor oil in the old car crowd. Insurance is about protecting your assets and your future. Not just the physical camper in this case but your other assets too if something absolutely horrible would happen. Now I am fully covered under State Farm for all my insurance policies. Reason being is I have an umbrella policy. If I went with a specialty insurance carrier for the camper or my old car the umbrella policy would not cover those items. Now with my old car, I am paying just a little bit more than I would with a specialty insurance carrier, but I am much better covered incase of a horrible accident.
Personally, I would talk with your insurance agent, talk about options and the pros and cons of doing different options. My State Farm agent was very good and took the time to explain my coverage, exemptions, loop holes and so for. At the end of the day she did not pressure me to stay. But gave me a lot of good info to my research in looking at options.