Try a jumpsuit for the whole day, not just the mirror
A one-piece outfit makes color and coordination easy. Fit is different because the top and bottom move together. Before wearing a jumpsuit for several hours, check how it behaves when you sit, reach and use the fastening on your own.
Give the torso room to move
Put the garment on with the underlayers you will actually wear. Sit down and then reach above your head. Check whether the shoulder straps or armholes pull and whether the seat feels tight as you bend. A waist tie can help define the shape but cannot add torso length; loosen it or try a different cut if movement still pulls. If you prefer separates, a top and trousers in one color can give a similar visual effect.
Plan the layer and shoes together
For a sleeveless piece, try a cardigan or jacket you can remove easily. Check that its sleeves do not crowd the armholes. The picture is seated and does not show shoes, so choose yours based on the venue and distance. Take a step up and see if the hem stays clear. Check whether the fastening is easy to reach with your layer off.
Spend five minutes in it at home
Sit, walk and open and close the fastening yourself. If one of these actions is difficult when you have time, it will be harder in a hurry. Choose the one-piece version when it works through all the movements you expect that day.