No personal experience, but it sounds like you've made a pretty good structure out of it. What's the worst that happens, a slight divot in the middle? My platform bed has a slight mound in the middle where the metal bar is (there are wood slats from the middle to each side), despite our having put plywood under the mattress. It's less with a foam topper (but used to look huge when we had a feather bed that increased the divot effect!). We honestly don't worry about it.

Lori, we talked about getting a new "bed in a box" option. Did the research on which brand we'd like best and everything. There are so many now! But as newlyweds on a budget, we want to use the twin mattresses and box springs we already have if we can.

My friend had two twin beds pushed together to make a king. It worked for the most part, although there were times when it dog jumped on the bed that they would separate. Yours seems to be strapped together well. I would use them and in the mean time save up for a bed in the box in case you find the twins don't work.

My mother had her twin craftmatic beds at her second home. We were going to stay there temporarily after we sold our home & between purchasing a new one & she said we could push them together to make a king; the frames did have a connector for that purpose but we always had problems with the mattresses separating & creating a space between them regardless of whether their was a "bedroom activity" involved however I have seem this question posted before & was shot down by many for my response that we had issues with the mattress separating & creating a space so it must work well for some. No problem in giving it the old college try & re-group if you need to.

If you have your twin beds on a king size metal frame....would not that hold them together? Or I believe if you are using two twin size metal bed frames, the frames can be strapped or fastened together....even if you have wood frames, they should be able to be fastened together.

If it's "extremely comfortable" , what's the problem? I doubt anyone is going to share regarding the other "activities" : ) but this is a common solution for those who prefer different mattress supports and I have not investigated the other issue but appears it's no problem. I hope you used xl twins. That's what "equals" a king. ( five inches longer than a regular twin) There are fillers made for this purpose

http://www.comforthouse.com/bedconnector.html?cmp=googleproducts&kw=bedconnector&gclid=EAIaIQobChMIuvTGkIze1QIViCOBCh35NAWMEAQYAiABEgJUsPD_BwE

https://www.amazon.com/Sleep-Innovations-Foam-Bed-Bridge/dp/B0053WHBSO

Jan, extremely comfortable for a few moments to test it out does not mean extremely comfortable for a few years : )

I personally have this option right now. I call it the "poor man's King Size Bed". We have 2 Ikea twin mattresses side by side (no "topper"). There is a HUGE benefit to this system = no "movement" transfer from one partner to the other. The mattresses isolate the movement to one side of the bed. That means an active sleeper won't disrupt the other.

We also find that we can pick and choose the mattress that is ideal for ourselves without worrying about compromising each other's comfort.

The king "topper" - as comfortable as it is - will transfer movement from one mattress to the other. But it won't be as noticeable as a regular sized king mattress. If you like the topper than go for it. You might want to try out the twin mattresses alone...and then see if you wish to add the topper at a later date. That's the beauty of this system...it is extremely flexible.

Good luck. I hope my experience helps. I will probably maintain this system for a very long time as the benefits far outweigh the occasional down-side.

The filler won't do anything but help when you both want the middle! But when one of you is tossing and turning? I bet you're going to love the arrangement ! You know what I mean by the middle, right⁉️

Is it okay to put a king mattress on 2 regular twin bed frames?