For those traveling from Canada, I found that Ingle Insurance (helpline@ingleinsurance.com) out of Toronto will cover me for peanuts ($25) as long as the racing is not considered professional and there are no cash prizes. Canadian insurers simply fly you home if your accident is serious and you are well enough to be flown. A friend of ours was flown home from New Hampshire to Nova Scotia in a private jet, rather than staying in the States for treatment after she broke her arm and her hip (not racing). Insurance company paid the bill.
AMA will also sell you a policy that I assume covers you for racing as well, as they are the sanctioning body at BUBs. It only covers the first $5000 to $15,000 depending on which level you buy, but it may qualify as insurance for SCTA as well.
In any case, it would be good to get something in writing that you will be covered for "time trials" at an amateur
event!
Tom