What options there are for protection of non-delivery or non-payment for deliverable forward contracts in the absence of clearing house? With volatile assets the spot price can be very different from delivery price. Motivation to fulfil the contract decreases as the difference between spot and delivery price increases.
Is the only option to require high enough margin/down payment that corresponds somewhat to the volatility of the underlying asset and the risk of each party involved in the contract? Is there some known model for this?