Hi @IamDeablo! Great to see another Vancouverite on the forum! I did the Whistler Gran Fondo in 2018 and 2019. I qualified for the 2020 UCI GranFondo World Champsionship, but unfortunately with the pandemic it is cancelled along with the Whistler Fondo.
On this thread - Vancouver, BC Gran Fondo first timer - #80 by brianv17 - I posted my training plan that I followed for the 2019 season (first year with TR). I copied it here for convenience.
In 2018, I finished the fondo in 4:26 and in 2019, I came in at 3:43! I think a big part of the success was the structured training via TrainerRoad which started in Oct 2018 (sweet spot base 1 and 2, sustained power build, sweet spot base 2, sustained power build, climbing road race). Over the season, I averaged 5 hours per week and a weekly TSS of 360. 2019 was my second year of structured training and the first with TR. By the way, I am 45 yrs old and 78 kgs; so I am also a masters athlete.
In 2020, I let Plan Builder build out my training season (from Oct 2019 to Sept 2020) with my A event being the Whistler GranFondo / World Championship (now cancelled). I would start with that route. The training plan it selected was pretty much the same as what I hand-picked in 2019; although this year I chose General Build for my first build phase to focus on my weakness.
Judging by your earlier post on your list of tips, you got an excellent grasp of the fundamentals. To re-iterate a common theme from the podcasts, training consistency is important - start with low volume; nail those workouts and then build up volume as time allows.