Well You could try poser 12 for 30 days on Windows 7 to see how well it works.  Since Poser 12 is based off o Poser 11 with more fixes if 12 Runs then 11 Should.  The only issue I could see is if a Major security flaw was discovered that would result in Windows 7 being disallowed from using the internet. At this point highly unlikely but still a small possibility.  Which would be the reason they say runs under Windows 10.

Poser 5, 6, 7, 8, Poser Pro 9 (2012), 10 (2014), 11, 12, 13