Don't be ridiculous. You can't fix such outrageous safety hazards with stickynotes and a promise to be careful.
Given your small generator, this is a 5 minute job. The supplies you'll need are 3 wire nuts, an appropriate length regular 20A extension cord, and a 3 foot 20A cord with male plug on one end, and bare wires on the other.
When the power fails, grab a flashlight. You shut off the main breaker and pull the cover off the panel. For each of the circuits you want to power, pull the hot wire off its breaker, and the same cable's neutral wire off the neutral bar. Then you nut all the hot wires together with short-cord hot, and all the neutrals together with short-cord neutral. Short-cord ground goes onto the ground bar (an extension wire may help).
It might help to go into the panel early and tag each wire by their location.
If you want to be fancy, bring the short cord in through a knockout with a clamp, and put the cover back on the panel. You can do this in advance too, just cap off hot and neutral. Ground can go on the ground bar permanently.
If you want to be very fancy, replace the short cord with an inlet you mount on the wall.
The short cord won't reach, so use a common 20A extension cord to get to the generator.
Crisis over, put the wires back the way you found them.
Now, this method just cost half what you were planning to spend. And that long extension cord you wanted to ruin, is still good.
Now, the vulnerability of this setup is that it has no circuit overload protection, except what the generator provides, but if you plug into a generator socket breakered at 20A, you will be mostly fine. 15A/14AWG wires could be overloaded, but only slightly, and that's improbable in a temporary situatuon where you are necessarily being careful with load.
The other vulnerability is that the panel guts are just splayed everywhere, and vulnerable to someone falling on it or tearing the wires apart, but you can fix that as described above.
You certainly would never, ever feed the buses. For one thing, it will not work, and there in the dark, you would discover this and do random stupid things trying to make it work, because that's what humans do. Seriously, read the NTSB report on Alaska Air 261.
For another, well, if you read up on how to make a suicide cord, you have also read up on what happens when an idiot makes an error with one. They kill linemen or their kid.
Yes, a cord with a plug on one end and bare wires on the other is also dangerous. That's why it's 3 feet long, to make it obvious. When you unfurl an extension cord, do you really check both ends to make sure the other one is a socket? I don't. So long extension cords should be normal.