i know naturally my post and like it. ;-) but this is a specific solution only for recurring sales invoices.
more interesting is the question, if the service module or an addin can be used to get a sales contract managament with according (recurring) invoices, especially for lending purposes.
i worked long time with the service module, seems, that it can be used for that purpose, also for lending.
additional blanked sales orders are an interesting base for that purpose ... with some changes. in that case the premium license is not needed.