How about spreading the “smaller guild” week around some?
(Smaller Guilds = FFA below)
Week 1
BI - Controller
Static - RD Base
VGE - GoBB
FFA - No raid
Week 2
FFA - Controller
BI - RD Base
Static - GoBB
VGE - No raid
Week 3
VGE - Controller
FFA - RD Base
BI - GoBB
Static - No raid
Week 4
Static - Controller
VGE - RD Base
FFA - GoBB
BI - No raid
And if in time a 4th guild wants in, its easily expanded, just add a 5th week?