Well after a bunch of downloads (26 to be exact...) and a total of 12 substitutions, the LSW Extension finally runs with all required assets. 7 subs were just to find the new file locations of existing assets, and the remaining 5 were to substitute something close, mostly vehicles. Here is the list of everything I downloaded to make the LSW run (Your mileage may vary...):
You can disregard the two ETS2 Scania truck d/l files and the RWA Veg mod and SD9 Updates.
My opinion now is that the LSW route is a very well-done extension to the RW&A Lakeside Route. It's apparent that much work was put into creating this content and I appreciate that. A bunch of hours were invested in making sure I had all the assets required, but in the end I think it's well worth it. It runs very well on my laptop with about 40-50 FPS on a regular basis.
On another note, the RWA Vegetation mod is a gorgeous addition to the basic RWA route and I highly recommend it.
I think I'm going to install the remaining RWA add-ons from the file library and play around a bit more with it. There are also a bunch of scenarios I think I'll look at.
More fun running trains!
Hope this helps anyone else who would like to use the LSW Extension.
Best,
Marc

Seriously, thanks for the time you spent on this project. In the near future, I will try your addition and see if it works for me.