Sending yourself a PM is about as good as I can think of if you want to stay purely on yacf. It sticks to the same BB code, and so it's pretty easy to copy the report across to a post when you are ready.
If it's for a multi day ride I'd also advise writing a report in serial posts as hatler suggests. It breaks up the report for the reader, and gives time for you to form the next bit. It's also how
www.crazyguyonabike.com reports are written, which is one of the sites that got me into cycle touring.
I haven't done a report (or a tour) for a while
but I used to do a day or two at a time. My style is normally a few pictures with some text to string the day together (CGOAB style), but there are some brilliantly written reports in the ride reports board with descriptions that really make you feel like you were there, and what the rider was thinking as they went