My power system is also layed out such that in interlock won't fit the bill. Main breaker is at the house, generator feed is at the barn, which is fed from the house. Things are clearly marked, wife and oldest son understand the process and order of events clearly.
I agree. I used to have the same set up, had to feed from a sub-panel in my remote garage. I was going to place an interlock on the main panel incorporating the sub panel breaker but never got around to it. I placed laminated magnetic instruction sheets on the panel door, the sub-panel door, and the generator, just in case I wasn't around and my wife had to start it. She understood it well and the instruction sheets just served as a reminder, but gave me a little peace of mind.
In our house now, I feed directly from the main panel, so I opted for the interlock. It is much better than the transfer switch because we didn't have to choose what circuits to power. We can run the whole house but we opt to stagger certain items. Like no need to run the dishwasher or washer and other appliances at the same time. Or don't use the toaster, and the coffee maker when the fridge is powered up. The basics all work fine together. We use a 10000 surge, 8500, and haven't heard it idle up much.