Dan,
Schafer's car actually WAS entered as an RT4 in early 80, regardless of what it actually was. It's notation did change in 1981 entry lists. Stefan's excellent site at
http://user.tninet.se/~aiq291w/F2_Index.htm shows the races.
Wyatt Stanley entered a TG280 in the first half of 1981, but the car never turned up to a race. Not sure about his Ralt in 1982