The OED entry for "bossy boots" cross-refers to the entry for "boots":
3. In various comb. (humorous or colloq.) = ‘Fellow, person’: as clumsy-, lazy-boots; see also SLY-BOOTS, SMOOTH-BOOTS. 1623 PERCIVALE Sp. Dict., Lisongero, a flatterer, a smooth boots. 1865DICKENSMut. Fr.IV. xi, You are the most creasing and tumbling Clumsy-Boots of a packer. 1832LYTTONEugene A. ii, ‘Why don't you rise, Mr. Lazyboots?’
Evidently "boots" has been used humorously or colloquially for "person" since at least the 17th century!