Don't get me wrong, the loading screen you mention will likely work, but it is far from optimal.
Most of the frame drops happen after the load, also due to objects initializing their states, where behaviors obviously require more performance.
Not to mention it taking longer to save/load the more objects your layouts has, which also requires a sophisticated loader mechanism to make it viable for the game matriax mentions.
The key is layouts with not to many objects on them, and careful with addressing them all. (the objects)
And switching between layouts smoothly can be done as easily as have a global black none transparent layer on top, lerping its opacity to 100% before switching to the next layout, which lerps the black layer back to 0% on layout start.