I did find a modded SecMms.apk with a fix baked in which does successfully add the actual sent time to the 'date_sent' field in the mmssms.db database; however this still does not accomplish the task of substituting the time sent in the timestamp that appears above each message. Also knowing that the SMS Sent Time app can locate the actual date/time sent gives me the belief that there has to be a way to get the timestamp in my conversations to use this value. Technically it wouldn't be the time I received it, but in cases where I'm in airplane mode for hours - as happens frequently - seeing that I received a text while my phone was off and knowing the time it was sent is more important that using a true time of receipt.
If I thought it was a limitation with JB 4.1.2 I would bite the bullet and update either to 4.3 or even to KitKat, but I like to think that it's possible yet the developers that do all this amazing work haven't found that Verizon SCH-i535 phone running TouchWiz Jellybean 4.1.2 to test on.
So does anyone have any ideas as to what I can try next?