When I lived in suits, and often had to go directly from a red-eye to a job site, I ... pause, this might get me banned.
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I wore a pants-liner I'd had made out of suit-lining material, under every pair of suit pants that wasn't fully lined. Putting it on was a fussy extra step and my grandmother, had she been aware, probably would have called me old-fashioned. But it eliminated the elephant-knee effect. A tailor had suggested it as a cheaper alternative to having RTW suit-pants lined, as I'd come in requesting.
Also, hitching the trousers up a bit before sitting down, grampa style.