First, I have no idea what the iron stain has to do with anything. Is that a factor in FC or CYA needs? No, just doing things one at a time. No real reason.
next, let's do the math on FC. Your pool is almost the same size as mine which is 23,000 gal. How fast does FC drop in your pool right now? Let's say 2 ppm/day but actually is it some % decline and if you boost higher it just goes away faster. But, let's say that you need an extra 6 ppm only. That is one jug of 6% bleach, plus another half. And you ought to expect that the FC is back to where it began when you return. That's what I'm thinking.
Now, if you think you want a bit of a safety margin, then add that floater in the pool. I know that in my pool 7 pucks from Leslie's adds 15 FC and CYA of 9. I know this because that is what my auto-chlorinator holds. So, the only question is how much of what is in the floater now will dissolve in 2.5 days? I will guess that only a part of one puck will actually be used up, but take a look at how many are in there and use the worst case. I'll guess it holds 3 or 4 so at worst you could see CYA go up by 5. So you are at 45. No problem, that is where you want to be for the heat of summer. I will probably put one puck in the floater the morning i leave, thanks for the idea
Re the skimmer. This time of year is not so bad, are you really having to clean the skimmer more than every other day right now? We are cleaning every other day and it is not bad, I wouldn't worry about 2.5 days. I would worry more about lack of circulation if the pump were off. It is really hot and sunny now. I'm not worried about the skimmer that was the other poster. The pool skim catches most everything and that bag is big
Are there any older kids in the neighborhood that have pools that you could hire for a quick visit to check the skimmers? Or a neighbor? Anyone with a pool would probably be willing to drop in for a moment to clean the skimmers since you'd do the same for them. Don't know any quite yet. This is our first year in the home. Good idea for the future, thanks.