Leaving aside the argument of whether being undead counts as being "dead," nothing stops the caster from preparing the ritual site, performing the ritual, and then, the next day, having rested thoroughly to have all his spell slots, ritually suiciding and having himself burried in the ritually-prepared plot.

Because it's 1% per spell slot, independent of level he might want to make copious use of Mordenkainen's Lucubration, too.