Does there happen to be any functionality where you can autolaunch a designated workflow from Salesforce?
I'm imaging a trigger, e.g. status = Verbal Commit and then the workflow launches automatically, the fields are prefilled and then the created document is sent automatically for signatures. Or, something like DocuSigns Power Forms where you create the template and you have an open link that is sent to the recipient to fill in their name, address, etc. and sign.