What exactly is your goal here? Why not use a simple mnemonic generated by the usual deterministic wallets? You can use that on your "mobile and PC with full access"...
I think he wanna kill two birds with one stone, i.e. have a vanity address and backup his vanity via SEED.
In my view the vanity address, in and of itself, is bad concept for the personal stash as it destroys privacy of that stash.
Thus, as being said, the usual deterministic wallet would be a rocking one.