So one problem I have noticed is the backtester does not simulate availability of funds accurately. First, for a Cash account, it assumes that once a sell order is fulfilled, those funds become available, when in reality it takes 3 days. For more rapid trading strategies that can cause problems in live trading (where trades can be rejected due to lack of funds). Is there functionality for a cash or margin account that lets you accurately determine intraday availability of funds that I'm missing?