IVERYAN First, congratulations! I hope you got a good deal on it and his loss is your gain! With a hydraulic stuffer, there should be no need to use 2 qts of water to a 25 lb batch to get it to stuff into 19mm casings. I can use my hand crank stuffer and use 1 qt of water and get it to stuff into 19mm casings on a 12mm stuffing tube.
Having said that, there isn’t really any major problem with your plan, just know that it is going to be almost soupy when you are stuffing it and while I didn’t you possibly could have some consistency issues. What I would imagine is that it would have hotdog like consistency.
If I were you I would do a smaller test batch first before committing to a 25 lb batch, just to be sure. You could even try mixing a few lb with 1 qt, a few lb with 2 qt and then mix the rest of your batch to whichever works best.
Also, yes, if you are using Encapsulated Citric Acid you don’t want to hold it overnight as the encapsulation might start breaking down. The sure cure can safely be held overnight, that isn’t any issue.