BUDHM:
I have done smaller briskets in my old SMO 009 without having to cut or fold them. I have done three 18 to 20 pound briskets in my SMO 045, and 5 in my SMO 66 without having to cut or fold them. The 045 and 066 have the same sized grills as your 025. This is sort of like trying to think outside the box, while remembering that you are fitting in a box. Put the point of the brisket in the front left corner of your grill, and then bend it so the end of the flat is in the back left corner of the grill. Your brisket may still be a little long. put your left hand on the point, and right hand on the flat and push them together. They will fit with a little room to spare. I think that when OLDSARG talked about trimming the thin fat cap and placing the trimming on top of the brisket, he was talking about cooking the brisket with the fat cap down, and placing the trimming directly on top of the meat side of the brisket and not on a top rack over the brisket.
Everyone goes through a learning process when they start using these smokers. I messed up enough smokes that my kids had Pizza Hut on speed dial. The good thing about doing BBQ is learning, making adjustments, and, asking other people how you can make it better. I forgot to tell you to read the 101's that Smokin Okie put together. You can't go wrong with any of his methods. There are little tips, tricks, and watch out for things that have been written about over the years. I hope your cook went well, and brisket turned out great.