This is a simple and yet very important reminders for people who wanted to or prefer to jot down their seed phrase in a paper than saving it on a notepad. Although I don't use this method (manual writing on a paper) since I am using electrum, I can copy it on a notepad and print it on a paper if I wanted to save a back up of the seed phrase outside my computer.
I don't understand why you would want to go through this hassle, just generate your seed phrase and write it down on paper, your seed phrase should not be written in your notepad or stored somewhere in your computer.
Aside from that I always get the private key of the address I used for receiving and then import it to just have a solo address for receiving(this is to prevent remaining BTC to be sent to other address when transacting part of the BTC held on that address). This way I have two options in recovering the address, one is through the seed phrase and the other one is through the private key.
Using one address only is not good for your privacy and there is no need to back up a private key belonging to one of your addresses. You are somewhat complicating things imo, just do it the "simple" way, back up your seed phrase which can generate all the addresses in your wallet and keep the backup very safe.