Interesting you need more weight and cable to fish Gull Lake......I thought it was around 80' max??
I use a Scotty Depthmaster in my PA-14 and typically fish, in the 25-40' depth range for German Browns and large Rainbows here in Oregon......I use a 2.5# lead weight and have never caught a fish trolling below 50' depth.....I see an occasional large fish displayed at 125', but never hooked one, when trolling down there for some unknown reason....the deepest hole in the lake I fish is 180' deep.
I have used a 4# lead weight and decided the extra drag did not buy me any more success than the 2.5 # weight.....so, I save my energy moving the 4# weight around as I normally cover 7 to 8 surface miles at 1.7 mph average trolling speed.
Now, if you were fishing in the ocean at 200 or 300', 4#'s would be "light weight"!
Good luck trolling in the Sierras.....I loved fishing the June Lake Loop area lakes as a teenage, 55 years ago