Did you discuss with your FI consultant before posting here? There are many ways to handle this from FI side. Yes from SD side, there is a provision to post the amount in FI to some provisional G/L Account and later on converted into Sales Account but as you expected, this cannot be automated. To post the amount to provisional account, you can have the pricing condition type as Accrual and have G/L accounts in VKOA accordingly
G. Lakshmipathi