I've no experience with insuring a toy hauler, but it would think it wouldn't be drastically different from other trailers. With the caveat that the value of the 'toys' being carried potentially changes the game somewhat. So you need to evaluate how those are covered.
Personally, I have a policy with Farmers that includes both my boat & trailer, so I get a bit of discount from the combined policy. You may want to check to see if you have a similar option with current auto insurance carrier. That way you have some idea of the level of service. I have no beef with Farmers, on the other hand I haven't filed any claims either.
I know Good Sam Club offers insurance and they claim that since they only insure RVs. trailers, and the like that they understand the needs better and therefore have better coverage for the cost. It sounds plausible and I've heard some good things from other people on forums but I have no personal experience with them - one way or the other.
If I were a betting man, I would say that most insurance companies would require you to have a separate policy on the "toys".
I went ahead and got State Farm on my 189FDS ( not a toy hauler ), but I am going to shop around before it comes due again and see if I can beat their price. I believe the way State Farm writes their policy is like this: let's say I'm pulling into your driveway with my truck and trailer, and I clip your car with my trailer. I believe it's actually the liability policy on the truck that would pay. So in other words, I could have no insurance on the trailer, and yet the loss to your property would still be covered. However, in the example given, I would have to have separate policy on the trailer to collect for the damages I did to my trailer.
Another example is if I am pulling the trailer, and let's say it came off the hitch and crashed into other traffic, it again would be the liability on the truck that would pay.
Obviously, these are all specifics you need to address with the agent or company you are shopping with.
I got a quote from Blue Sky for $200 annual. I've read no negatives about the company but I'm going to check with the independent agent where I have my homeowners and car and pickup insured .. all with Auto Owners.
I've checked other companies to try and get better coverage and or lower premiums and NO ONE has even come close to what I pay Auto Owners for identical coverage.
However, I do not know if AO writes RV insurance so will see what my independent local agent comes up with.
When I left home to pickup my new XT276, I called my local independent agent and bound coverage on the Toy Hauler just in case some unfortunate incident would occur bringing it home some 400 miles.
After getting it home, I visited with my agent. We did an endorsement on my homeowners policy to cover the toy hauler and contents. My cost was only $128.00 a year. I think that is great. Homeowners/tow vehicle policy are with the same company.
The toys within the toy hauler would be covered by their own policy of course.
2012 Fun Finder XT 276 Toy Hauler & Harley Davidson Ultra Classic with Condor wheel chock
2014 Dodge Ram 2500 AT 4X4 Crew Cab 6.4 L Hemi, 373 gears, tow package, Rambox option, Revolver X2 tonneau cover, Equal-I-zer anti-sway hitch.