ABOUT BOX SPRINGS:
I am not a fan of box springs - in my opinion, they are a plot on the part of the bedding industry. In most of the world outside the US, they are unheard of. If you look inside of a mattress and of a box spring, you will see that there is very little in a box spring - they are cheap to make. Yet they commonly are half the cost of the set. They are the profit maker.
Mattress salesmen will often tell you that a box spring will make the mattress last longer. (I question this) Once I tried to pin one down, and asked "How much longer?" Fifty percent longer, he told me. Yet it adds one hundred percent to the cost of the mattress. Any way that you look at it, the arithmetic is not there.
They will sometimes try to scare you that "Using your mattress without a box spring will void your warranty". Well, I have built and sold many hundreds of beds since 1983, and I have never once heard of anyone making use of the "warranty" on their mattress.
In fact, I think, box springs do you harm. They are a source of sagging and non-support as they age. Frequently, somebody with back trouble will put a sheet of plywood between the mattress and the box spring, and feel better. That really forces one to ask what good the box spring is doing.
HOWEVER, there is no question that mine is a minority opinion on this subject. I have built many beds for use with box springs. And please note that I do it routinely and cheerfully, without giving anybody a hard time. If you choose to use a box spring, please let me know, as I will need to adapt the bed to accommodate.
THANK YOU for listening to my opinion, and I will build your bed the way that you want it built.