Where did you find the date on this set of jumps? As the Kyoto Museum exhibit Revolution in Fashion 1715-1815 only dates them as Early 18th century... but it does list them as jumps and not a waistcoat. Their description being Jumps, quilted linen with plant pattern, tied in front with silk taffeta ribbons. They also state in their glossary: Jumps: Woman's soft bodice without boning, usually worn at home instead of a corset. So odds are this particular set are not boned at all.
The jacket in the back right is also listed as early 18th century, silk satin with diamond-patterned quilting. This might be something to consider for undress as the sack backs were coming in already toward the end of the GAoP.
Oops sorry you can see the jacket in the far right back ...