Hi,
A few things...
If you are getting it with the 3M backing (I recommend you do) then no... you don't need anything extra. BUT... I do recommend that you wash the boat well with a good detergent (not car wash soap with wax and polymers) and go get a small can of Acetone from the hardware store to clean the spot where the mat will be getting put. The Acetone will clean any left over wax, and oxidized gel coat to make the bond as strong as it can get.
Second... I know the dark gray may match your boat... but a dark color may get hot in the sun. I know even the teal mats in my boat will get hot. It's easy enough to throw a little water on them to cool them off... but I thought I would just throw that out there for you to think about. (that's also why my seats are white, and light gray)
Last thing... when you do the install... it's best if you can do it on a semi warm day with the sun out. The heat will help the glue on the mats to adhere better. Also... press hard for a few minuets to set the adhesive.
Follow my recomendations... and you won't have any lifting edges, and they should last for a long time.