Bad idea. You need to do TWO things--1.prepare the boat to sit...and 2. Recommission its systems for use when you return. You're trying to do them backwards and not a very good job of either.
Bleach is highly corrosive. Which is why, if you've read the directions for recommissioning a tank I've posted here many times, you've seen that the bleach solution remains in the system no longer than 24 hours...'cuz that's as long as any "purifying" properties last, leaving only the corrosive properties behind.
So just drain the tank or top it off, when you're ready to let the boat sit...then recommission the fresh water system when you return.
You haven't asked about how to leave your sanitation system. Pump out and thoroughly rinse out the holding tank (I've recently posted instructions for doing that in two "winterizing" threads here). Also rinse all the plumbing out, especially any overboard discharge pump and related plumbing.
You can find instructions for all of this in the archives here...but they're also included both in my books (see link in my signature--just click on the title) and a WHOLE lot easier to find in either of them.
--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein