How do make travel insurance template with guest information?

I have a guest paying by check. They want to purchase travel insurance too.
*How do I make a template for that guest that has not yet converted to a booking until the check clears?
*Can they purchase the travel insurance now or must they wait until they are officially booked?

Our situation:
I have blocked the dates for a guest. The guest will be signing our DocuSign contract and sending us a check for the downpayment. Once the check is cleared I plan to revert the block to a booking.

They pretty much can't:

https://www.ownerrez.com/support/articles/travel-insurance-common-issues-questions#no-card

If they want to purchase travel insurance, it needs to be a booking and they'll have to make the travel insurance on a credit card. They can still make the booking payment to you via check.

Convert the block to a booking and you'll be able to send them a travel insurance purchase link from the Insurance tab of the booking. If they end up not sending you the check and going through with the booking for whatever reason, then cancel the booking.

I'd recommend having them wait until they're sure they're going to book before purchasing the insurance policy. Once they purchase the policy they'd have to contact the insurance company to cancel it.