I can write the 3 seeds on a paper with a pen but what about the pub keys 
Too many characters and a huge risk of mistyping.
Any solution/idea ?
You can have digital copy of the pub keys. Anyone who have access of all the Master Pubic key does not mean they can restore the main wallet. As per my understanding it will restore a watch only wallet. With a watch only wallet they can not move the coin so you are safe.Too many characters and a huge risk of mistyping.
Any solution/idea ?
Seeds are what you need to keep very safe. Worry about the seeds.