I finally got the water tanks cleaned, closed up, plumbed, and ready to be attached to the rest of the boat.
With the centre tanks, I had to make new baffles, so I started with a sheet of 1/8 inch aluminum and traced the baffles from the other side.

I cut and riveted on the braceing pieces.  I used a potable epoxy to put nuts in the end of pipes.

Then I installed them:

I then added new gasket material.  A food grade gasket material.  I got thick gasket material to help seal the lids.  1/8".  I think 1/16" would have been fine.  I didn't visualize how thick it would be.  So I had to get longer bolts.  But now it is done.

The forward V birth water tank had another issue to deal with.  At some point the boat was equipped with a water maker and the owners felt that they didn't need the extra tank. So they cut a much larger hole in the top.  So I cut a new piece of aluminum that was 1 inch bigger on all sides and with a gasket in between riveted it on .  In the hole of that, I cut a regular shape hole and riveted that piece on as well.  All the fitting are now attached.
You will notice that there is one extra attachment.  
1.  The fill
2.  The outtake
3.  The vent
4.  The return.
5.  Little thing is the Tank tender system.
I am setting up the tanks so that water can be moved between tanks and filtered in the process.

I am using PEX pipe.  By the way, I discovered something.  A 1/2 inch pex pipe fits almost perfectly into a 5/8 inch flex pipe.  I of course discovered this AFTER I bought a bunch of fittings.  Just add an o clamp.