As said here before 24 mnemonic words from the BIP39 set of words encode a 256-bit random number and include also a partial hash checksum which allows very certain detection of an error in the sequence of words. To me your 128-char mnemonic passphrase is a bit of over the top. It's random which is good, likely very few humans can type it without any error which is a risk. That means you have to store your mnemonic passphrase in a digital file on a computer which shouldn't ever go online for safety reasons. Practically you can only copy/paste such a mnemonic passphrase. If you care for security this mandates that you don't use any online device with such a mnemonic passphrase and it makes an analog copy of the passphrase nearly impossible as the smallest error will give you a different and empty wallet.

You're making your life harder than necessary. You can't have a hierarchical deterministic wallet with fancy addresses, very unlikely to happen. Vanitygen addresses might be fancy but are a pain to generate securely and to keep secure, too.

Get a decent hardware wallet (and that's no Ledger crap device) and have piece of mind. Learn on HD wallets and derivation paths e.g. at https://learnmeabitcoin.com and make yourself familiar with a good hardware wallet. Practice recovery with some Testnet bitcoins and you will have a much more secure storage of your wallet than with any online software wallet solution.