Good morning and happy Halloween.
i followed your link to petco and there is a pic of the AI style light. I have 3 on my 48" x 18" 75 gal and they are very nice, producing plenty of light for illumination and soft coral. i have also used Current USA LED's for softies but they were insufficient for zoas and lps. I don't have AIO experience except for the friend who tore his down because of the constant algae overgrowth was not kept in check and family time overtook the effort, his corals and clown are still doing well in my tank.
I have the same RODI system and it has been great for me.
The tank level issue is one for auto top off. you can keep the level within 1/2" in the back with a simple system.
i have a couple of types of skimmers and they are both subject to what you describe. the start up of a skimmer has a break in cycle when you start it. in my case that is when it is new
and when it has been off for awhile. the initial period may be due to manufacturing. if there is residue on the internal surfaces that need to wear off or there is nothing on the surface and it needs to have a film to work right i do not know. the fact is that each body of water has some level of accumulated protein. the skimmer at what ever setting starts dealing with this protein and produces an amount of skimmate. this reduces the concentration in the tank and the skimmer then produces less skimmate per hour. until an equilibrium is reached between protein produced and protein removed the skimmer seems to be 'tempermental'. One thing i did was to put an oversized simmer on a very low load tank. this was unnecessary because there was actually not enough protein to develop a dark skimmate so i was just removing water because i adjusted it so bubbles would come out of the top,
I have what would be termed nuisance algae. i don't sweat it too much, probably because i am in the learning stage and I figure that it is biodiversity.
thanks for your post, and enjoy. definitely post pictures