Instead of loading systemcompatible.manifest as the implicit activation context, load forwardcompatible.manifest
Add a new assembly containing all apisets called ReactOS.Apisets and make it a dependency to forwardcompatible.manifest
I use a (not yet used) dir-id value of "80" for this purpose (the value
"8" being already used for /bin/testdata/ and of course values from 9 up
to 50+ are also already used... >_>).