How to process sales application for payments

I have an architect client that I am going to migrate from Sage 50 to Business Cloud, this type of business is one of the many that use Applications for Payment instead of Sales invoices, much like lawyers and construction companies.

Currently I issue an application for payment, separate nominal code from sales using a T9 VAT code with a VAT amount in the VAT box, this then posts to the customer ledger to allow statements to be sent.  This method also allows management accounts to be processed showing total sales, applications for payment and VAT Liability including the possible VAT from the applications.

Does anyone know of an addon or a work around that will let me process Applications for payment in Business Cloud,  I need the transactions to show on the customer ledger, P & L and Balance sheet at full face value but not go through a VAT Return as the sale is not agreed until the client accepts the application and agrees to pay.  I can't use Cash VAT accounting as the annual turnover is over the threshold and some applications can take months to be agreed.

Thanks