We have a friend who is a Notary and she did the paperwork for us before we left. April 13 was significant for us, but that date wasn't available for our DW, so we did our legal paperwork on that day - but still had our friend submit the paperwork on our DW day of April 19 so that is the date on file with the courthouse.
We did the legal stuff ahead of time for a few reasons - one being that the paperwork from the DR takes up to 6-months to receieve back in the US ... yet we only have 30-days from our wedding date to change insurance, etc. Also, we felt it better to do ahead of time rather than after just in case anything happened while we were traveling. Morbid, perhaps, but you really never know...