Putting a Queen-sized Mattress on a King-sized box spring

Someone at a mattress store said they wouldn’t recommend putting a queen-sized bed on a king-sized box spring. Would doing this cause any problems with the mattress or the quality of sleep on it?

JBR202:

Safe ingress and egress would be the issue. Even with the mattress centered upon the foundations, you’ll have 8" of foundation exposed on the left and right side of the mattress that you’ll have to hop over to get in and out of bed. Or you’ll end up stepping on the foundations to get in and out of bed, in which case you’ll most likely ruin the foundations in short order. Additionally, the foundations will lack the extra reinforcement that they normally would have along the left and right sides if they was sized correctly to match the mattress. If this was short term solution (waiting for a new platform bed, new furniture, etc.), I can see this being a temporary fix. But it’s not something I’d recommend long term.

Could the mattress be put on the side of the box spring instead of centered on it?

Could the queen mattress be put on the side of the box spring instead of centered on it?