I think that two ledgers is overkill. I mean, if anything happens with the first one, you can order a second one and recover from the seed.
Another thing is about the placement. If you want super safety, keep the backup in another city. Maybe send your second ledger to your grandparents or something like that. Or keep it at home without the seed in it. (Just keeping too many ledgers at home may lead to
the 5$ wrench security issue if one finds them)
The seed, on the other hand, is the most important thing and imho the easiest to conceal. Get two books, mark the seed words in them (make sure you keep the ordering right too), keep one at home, keep the second at your parents/grandparents/uncle/whatever. Of course, the marking should not be so obvious, for example keep somewhere (on a specially made/printed bookmark?) a list with page numbers and word numbers.
I would not rely solely on memorizing. It's prone to the 5$ wrench issue and an accident can make you partly lose your memory and you'll lose everything.