I believe it was Fubar who figured this one out - someone correct me if I'm wrong so I credit correctly, but yes, you can add a g-limiter to your plane.
Add this to the [Fuselage] section of the aircraft data.ini:
SystemName[XXX]=CAT1_G_Limiter
(NOTE: Add the next number iteration from the Fuselage section. For example, if the last entry was SystemName[028]=RightStab, you'd name the limiter SystemName[029]=CAT1_G_Limiter)
Then, somewhere below that (I usually keep it in the section which defines the wings, vert tails, stabs, etc.):
[CAT1_G_Limiter]
SystemType=HIGHLIFT_DEVICE
DeploymentMethod=AUTOMATIC_G_loading
CLiftdc=-2.7500
CDdc=0.0
Cmdc=-0.350
AreaRatio=2.000
SmoothDeployment=TRUE
Setting[1].Angle=45.0
Setting[1].DeployValue=7.33
Setting[1].RetractValue=7.25
MaxDeflection=20.0
MinDeflection=0.0
ControlRate=5.0
ModelNodeName=Internal
For this example, the g-limit is set to 7.33g. I think the retract value can be closer to the deploy value, but I don't think they can be the same, and retract should be slightly below deploy. So, if you want your F/A-18 to follow its nominal symmetric g-limit of 7.5, or even a slight overshoot to 8.0, you can set the DeployValue= to, say 7.55 or 8.0 or something thereabouts. The retract value should be something like 7.45 or 7.95, respectively. Play with it a bit to see what works best.