I think Scaife or Boulware starts at LG & Hillery eventually gets snaps at RT if Donaldson struggles there.
Said back in Feb before Spring camp the lineup would be:
LT - St. Louis/ Herbert/ Johnson
LG - Scaife/Boulware/Jones
C - Gauthier/ Gaynor/ Milo
RG - Donaldson/ Mahoney/ Reed
RT - Hillery/...