How can I save mail messages on iPad

Question

I (strictly, my wife) have just bought a WiFi-only iPad to replace an ageing MacBook, and I also have an iMac.  I have a need to store and organize a limited number of Mail messages in the iPad, such that they are available in the future when I do not have internet access - i.e. while travelling.  These are varied, but typically contain reference information, reservation details, receipts, directions, etc.
Previously, this was easy to do with the MacBook.  I set up our GMail account as POP3, and filed such messages as we needed in as many Filed Mail mailboxes as I wanted.  Unfortunately, if you set up a Mail account as POP on the iPad, you can't define Filed Mail mailboxes.  And if you set up the account as IMAP, you don't have access to your filed mail when not connected to the internet.  So you're damned if you do, and damned if you don't.
So here's the question.  Is there any organised way to save messages permanently on the iPad?  And any attachments need to be kept as well.  While strictly they no longer need to be in Mail format (i.e. can't be forwarded or replied to), that would be a less convenient approach, and those all-important attachments would have to be dealt with.  But I am willing to be flexible.
And before anyone says that POP will not work with multiple devices, GMail POP has a feature that allows the same email to be downloaded to multiple devices as well as being held on the server if required, and all sent emails are also echoed back to all devices (the "recent" feature).  This has worked fantastically up to now.
Any help would be appreciated.

Answer 1

Do you need to be able to initiate this entirely from the iPad, or would it be acceptable to have to use one of your Macs when you save one of the limited number of messages? If involving a Mac would be acceptable, I can see ways to work around the iPad's lack of local mailbox storage.
You could use one of the various free cloud storage services that allow general file storage and local retention on the iPad (for example, Dropbox or Dump Truck, but not iCloud).
For Dropbox, you would make a folder for this cluster of saved messages inside Dropbix. For each message you want to save, create a folder inside that cluster folder, do a "Save As..." in Mac Mail.app for the text body, then a "Save Attachments..." if appropriate. (The inner folder wouldn't be strictly necessary for messages without attachments, but I suggest it for consistency.)
The key part is to open Dropbox on the iPad and mark the message and attachments as favorites (starred). That causes Dropbox to preload them on the iPad and retain them there until they are unstarred (lose favor).
You could probably do something similar with Evernote and favorites.