I did one years ago. I believe quite a few others here have also (saw a few in a recent thread).
If you ever get the other Hallmark/Springbok one, rest assured it's probably just as challenging for different reasons like the clouds and the smoke from the steamers! 
I'm no puzzle expert, but based on how you said you were proceeding, I'd recommend a possible different path. There's no real benefit to doing the border first (unless it's going to bug you immensely if you don't! 
).
I'd instead group by color schemes, then try to assemble chunks to make the trains. Example, try to pull out all the blue ones and then assemble what I am pretty sure is the Blue Comet next to the Water Tower. Maybe then pick out pieces with red and white in them to try to make the Fire Car and the Gateman. Then yellow for the 2 UP diesels, the caboose and Burro Crane is another path, etc.
Have fun!
-Dave
