While most of the folks here may know this I though I'd bring it up anyway. If you have roadsite assistance on your tow vehicle's insurance policy, it will NOT cover trailers you're towing. The only way your trailer would get towed under insurance roadside coverage is if the trailer is also insured and has roadsite coverage on it's policy.
Or... if you're like me with a '67 Shasta that cost me $500 plus maybe $1000 for repairs/upgrades, appliances, accessories, etc. and don't see much point in spending hundreds of dollars a year on insurance for the trailer, then you will probably want to get something like GoodSam Emergency RoadSide service which WILL tow your tow vehicle *and* trailer/5th wheel.
A tow vehicle insurance's roadside assiastance alone will NOT cover your trailer and you will have to leave it behind or pay out of pocket to have it towed seperately, so if you have a trailer that isn't insured that you don't want to have to pay out of pocket to have towed or leave behind on the side of the road should your tow vehicle break down, you will definately want some kind of actual RV roadside assistance for a mere $100 a year (currently $79.95 online for GoodSam members; normal price $109.95). Please note they do have two different plans so make sure to compare the two to see if you might prefer the "platinum" to the standard plan. ( http://www.goodsamers.com/compare.cfm
This also applies to boat/utility trailers and probably car dollies as well. I will definately be getting GoodSam's roadside coverage and I recommend it to anyone who is currently only relying on their tow vehicle insurance's roadside coverage. It won't cover your trailer unless they can double tow your vehicle with the trailer still attached (make a single tow trip).