I’ve used Advanced Rocketry with no issues before.
And yes that’s the way you need to do it if you want things to work unfortunately. You can get lucky but invariably something will bork.
This is how I did it. I tested batches of mods, then added those batches into bigger batches, all without GT as it takes longer to load. Once I had all the mods I could running I loaded GT by itself to confirm it was working then added the large batch list in with GT, then fixed errors on top of that. It was a long arduous task.
The truth of the matter is after I got the game working it ran poorly, so I ended up cutting a lot back out again.
Even if you get it running it may still crash a lot, you need to consider if you really need all of those mods.