I have done something similar before with Infopath 2003 a couple of years ago. I used submission via email though. The advantages of using the email is that it will sit in the outbox of outlook.
all our forms were emailed to a specific email address with a windows service that polled the inbox of the recieving mailbox to extract the form and continue with the workflow. found this was easier path to take than trying to submit to a public webservice. one was almost submit and forget (apart from opening email). Your scenario requires that the user fill out a form during the day and then remembering to submit when they are next connected to the internet is just asking for trouble, IMO.
People will tend to forget that they have to reopen the form and submit it next time they are online whereas if you submit it via email then the only thing they need to do is open and read their email at the end of the day.
I all comes down to user behaviour. if your users are willing to go through the processes that you are thinking about, then yes it is possible to do what you are suggesting.