You don't have to add 15 pages of checksums: you can also do one checksum per page. It depends on how accurate your OCR or typing skills are.
I think the OCR engine is pretty accurate. It seems to have only had a small amount of errors maybe about 4 or 5 on that single page of 3000 plus characters. I think that's acceptable but I really haven't put it to the ultimate test yet which is actually making a printout and scanning it back in. I just used a digital file with the OCR so far. I expect the results to be worse.
And maybe that one page was just a lucky one. I'll need to do alot more testing to see what the average case is. I hate typing so I need the error rate to be very low.
Error correction would be better, and that easily puts you back at QR-codes again (where you can choose the level of error correction).
Did I mention how much I hate having to do manual error correction? This QR code idea intrigues me and yet somehow I'm worried that if I tried to make some huge qr codes to backup my 100kb file (or 90ish), I might run into problems actually being able to scan it back in. You know, my android phone can't handle those because I tested it. It just wont read big ones. At all.