Just to repeat from above ... one piggy needs at least a 2x3, add a grid in length for each additional piggies (meaning 2x4 for 2 pigs, 2x5 for 3 pigs, 2x6 for 4 pigs and so on).
I also think that even with one pig, having a second water bottle as a safe gard is a food idea. Especially since you said that you sometimes skip a day in the cleanout. What if one gets clogged? Or broken? Or emptied? Or if more than one pig needs a drink at the same time? For 4 pigs, I'd say go to 3 bottles ... at least. (As I return to pics I see bricks on the other side, is there a second bottle there already?)
Also, the loft space that you have don't really count as their square footage, you might find that having a single, but larger loft would work out better. And with 4 piggies, I'd also suggest a second ramp to get to / from the space so that one pig doesn't trap another. The ramps also need to be secured with something much more secure than the rope that it appears to be secured with.
One last thing . .. from the pictures it looks as though the cage is located in an unfinished basement. This isn't ideal as they are social animals that benefit from being around us, it is also so much easier to keep an eye on their health when they are nearby. They are prey animals and hide illness very well. A piggies can go from fine to dead in a few days. It is always better to catch signs of illness early, and them being where you aren't for the majority of the day makes that so much harder. Again, this is based on appearance in the pictures. There is also risk for mold / mildew / large amounts of dust in the basement ... all are causes of URIs.
Please know that I am not saying that anything you are doing is wrong, just sharing what I've picked up on the forum and based upon my best guesses from the pictures you shared.
As far as fleece maintenance, I do a spot sweep every morning after they have breakfast. (Well, after I return from taking my daughter to school, they get breakfast before we do.) I also give the food bowels a cleaning then as needed. Once a week, I do a full cleanout / fleece change. Having taught fleece makes that so much easier to sweep. Right now I have fleece-towel-uhaul-towel-fleece flippable full 2x4 grid pad in place and it is weighted enough that it stays pretty much in place.