You do not need a UV for your tanks. Some people do need them for things they keep. It's recommended if you keep frogs, or turtles with your fish, but typical tanks rarely need them. I have UV's running, but only on my koi tanks because they are more prone to disease than almost any fish out there believe it or not.
I have rays, frontosa, flowerhorn, shrimp, puffer, SA/CA cichlids, bichirs, guppies, sturgeons... I have no uv's on any of them. I understand how you think tying them together would be best, and how if something has it, and you don't know, you can spread it even if individual.. but the chances aren't too high.
For me, (and this may work for you) my tanks go through a series of things, and so far it's been great and I've not had any issues with fish in over a year (with the exception of my FH with internals).. once a month, they get treated with something. This is how I work things.
Month 1: Temp 75 F, treat with .3% solar salt (skip water change for 3 days)
Month 2: Temp 72 F, treat with oxytetracycline (bi furan, binox) Leave in for 48 hours.
Month 3: Temp 76 F, treat with Ich tab Leave for 48 hours
Month 4: No treatment.
Month 5 resume.
Now, I don't always do this.. but when I was going through my KHA training, I learned that many people don't QT their fish correctly, and so many illness's don't come out until AFTER they have been in your tank for some time. Now, QT for Koi is 6 weeks long, and much more complicated.. but I have found that my rendition of it for tropicals has been pretty awesome. I had ich once in my 180 SA/CA tank.. my oldest fish, an 8 year old convict was on deaths door.. within 48 hours, he was ich free and back to his old self. I haven't had any issues since.
You stated: "I commend the fact you can care for your animals I simply can't." If you can't care for your animals, then really... you shouldn't have them. Part of having fish is keeping good husbandry skills, and if you can't provide that, then you are only giving your fish a miserable life. Find another hobby. I often work 60 hours weeks at my job, and when I come home, I don't want to have anything to do with my fish, but I know that I took on the responsibility of keeping these guys, and so, I get up and I give them the attention that I promised to give them. Fish keeping is a rewarding hobby, and one day I do plan on making this into a career.
I am also going to suggest that you look into your fish diseases.. raising the temps, and salting won't get rid of everything, and for the things it does treat, it's eventually going to grow resistant, so you need to mix up your treatments. You stated that you had an incurable bacterial disease that killed off your stock.. there is no incurable bacterial diseases. Even if your fish had dropsy, it's still curable to a point. It could have come down to the fact that you thought salt would work, or you just didn't catch it in time.
Point blank: you can tie your system together, and do whatever you want with your fish; but when they come down with something, and you lose it all again... re think what I told you because you will be kicking yourself later for not doing things the better way. Separate is always better because cross contamination is less likely.