Note that there are some minor bugs there as mentioned above, for which I promised a pull request which I still did not create… Not sure how much that affects the result though.
As far as I know, the headers are always 13 bytes (as explained above), and the payload is just a number of bytes too, so 105 in your example. So in matthijs’ original sheet that’s 118 in total; in my version it’s 105 and 13.
By the way: Don’t. Send. Text. Don’t. Send. Text. It will eat your maximum air time with no good reason. Also, it seems #BAT:42# is a counter value? Then note that the headers already have a counter. [see responses below]