My idea would be something like (probably not complete):
install new vRLCM + vIDM + vRA from the easy installer
create a new (temp) cname for the new vRA8
import vRA 7.6 (if needed?)
migrate vIDM
migrate vRO
migrate vRA (yeah, migrate and rebuild)
switch the old vRA cname to the new vRA
Then just decom vRA 7.6 and the temp cname
or keep using the new cname and decom the old cname.