Honestly, think about it from this perspective. Whichever child is in the regular bed is going to crawl over the one in the trundle bed if they have a bad dream, get sick on them if they’re sick in the night, or (I saw this one happen more than a few times) push the trundle in when they’re mad at the one sleeping on the trundle & make it a pain to pull out or not let them pull out the trundle when it’s bedtime. Instead of a set of bunk beds or a trundle bed, why not get 2 beds & put them in the corner so their heads are facing each other? My father & step-mother did that for me & my younger sister when we were little. It worked to keep fighting pretty much at bay. More on reddit.com

Late post, but im doing it for the archives and google searchers. I have looked at every corner of the internet and spent 2 weeks nonstop looking at daybeds for my guest room. Birch Lane (higher end brand of Wayfair) is the ONLY strong solid wood day bed I found w trundle (unless you spend $$$$ w an Amish store). The SKU is CDCH1056. It's weight capacity is something like 700 lbs for the bed and 300 lbs for the trundle. Pricey at around $8-900 but again, it's the only bed you can find online boasting that weight capacity. Everything else is flimsy fake wood. I also liked that the bed can take 10" thick mattresses while the other flimsy daybeds only took 8". Good luck More on reddit.com

Sounds like you need the Japanese futon life. No frame, so there’s no weight limit. Just two futons, when not in use you fold them and stack them. More on reddit.com

My in-laws have one. The lift feature doesn't hold tight so the bed had a delightful two level effect with a little path in the middle. This make cuddling hard and leaves space for a chilly breeze. I had the pull out one from Ikea. It was meh okay. But at least it didn't sag. More on reddit.com