'all that' is nothing. the pots take up more room than anything. i use to stick em anywhere, flower room corners, sides of the veg table, shelves in the sun room, out on the patio, etc...
lophs stay small, and once you graft, your stock doesn't grow (and shouldn't be allowed to if it tries). only the scion will blow up, and you can cull pere like crazy, cuz it grows so fast.
i actually don't even grow pereskiopsis all the time, but buy a cutting or two when i'm planning on growing some cacti seeds.
they're just a bit bigger deal than mushrooms. the perk is, set it, and forget it. i enjoy the flowers, but honestly, other than a weekly summer watering, they just sit around by themselves... the little rectangle pots you saw in my pic are only about 4'' wide and 8'' long, 4'' tall... lol, six per pot, do the math.
lophs can get full sun, but have to be acclimated. indoors they'll be lime green, and you'll want to harden them off before going outdoor and especially full sun. trichs dig full sun, so they can go from first root to outdoors in about 12 days (increase direct light by one hour per day unless burn symptoms occur). sunburned cacti are easy to spot... they turn red. kind of a dark red, with bruising coloration (dark green, grey, purple). if you see this, your cacti is burnt. bring it to full shade, and wait. they generally recover in 2-3 weeks.
let me know if i can help you cat. you should find this a piece of cake. cacti are lincoln logs vs pot being lego's...