Something I learned after I did the first cushion is to weigh the cushion before you wash it -- that way you can tell when it is really dry, because it will weigh the same. Fortunately I still had a cushion the same size that I hadn't done yet so I could weigh it to know when both were dry. This foam is insidious, in that the top and edges can look and feel dry, but the core is still sopping wet -- just set it on a dry paper towel and lie on the cushion and you will see! But it can't fool you if you weigh it before you wash it...
Here's what I did to get enough of the water out that I could carry the cushions without risking tearing them from the weight
, or dripping large streams of water as I carried them outside to dry.
After doing the grape dance in the tub with bleach and water, I drained the tub and rolled the cushion up as tightly as I could to get most of the water out.
Then I put in just enough new freash water to cover the cushion, did a short grape dance, then drained again, and again rolled the cushion tightly to remove most of the water.
I did this 3 more times because I wanted all the bleach out of the cushions. I figure that each time I was diluting the remaining bleach by at least a factor of 5, so 4 rinses gives me a dilution ratio of 5 to the 4th power, or 625. I thought that would be good enough.
After the last rinse I had rolled the cushion up as tightly as I could to remove water, then I let it relax and stood it on edge in the tub for an hour. That got a lot of the remaining water to migrate to the lower edge. I squeezed out that edge by hand then quickly carried the cushion outside. Yeah, it still dripped but it wasn't running rivulets.
Once outside I used my wet/dry shop vacuum to suck out much of the remaining water, then let the cushion dry in the sun. It took several days here on the coast for it to dry.