HoneyBadger,
When I anticipate a long post I tend to work it up in notepad and then copy & paste it into the browser. This way if my connection falters or if there is a glitch, I can simply copy & paste again with little time lost.
This is especially useful if you have a heavily formatted topic that you need to edit occasionally. Edit the post and then copy the text with formatting code and links into notepad, make the desired changes then perform a select all, followed by a CNTRL+V to paste in the new text. Now if the submission bombs, you can recover easily.
For relatively short posts I will hit CNTRL+A (select all), and then CNTRL+C (copy) before submitting. If the post fails, all you need is CNTRL+V (paste) your work from the clipboard and continue.
Hope this helps to save you some headaches in the future.
(I spent several years struggling with dial-up and the corresponding connection time outs and learned not to trust my work with it.
)