This was another area in the famous skiing town of Woodstock. Here's twp listings that describe the area:
1939
(Ski
Trails in the East and How to Find Them)
The tow at Prosper
Hill is reached by taking VT 12, which turns left at Pine Tree Fork. Prosper
Hill is 1/2 mile beyond Woodstock
Hill. A large open slope with perfect skiing gradient is found
here. From the top of the tow skiers may take either steep or gentle runs.
Lunches and free parking available.
1948
(Vermont
Life Article-Ski Vermont!)
Prosper Hill is listed
here.