Dammit, I just wasted an hour confirming my beliefs? Oh well.

The answer is to copy how the BadMiner triggers work, replacing the current BadFarmer trigger with the following...

;------------------------------------------
Trigger governing6
WhenToTest GovernorBuildingCompleted

Condition not SettlementBuildingFinished = farms
and AdviseBuild = farms

Affects BadFarmer 1 Chance 100
;------------------------------------------
Trigger governing6a
WhenToTest GovernorBuildingCompleted

Condition not SettlementBuildingFinished = farms+1
and AdviseBuild = farms+1

Affects BadFarmer 1 Chance 100
;------------------------------------------
Trigger governing6b
WhenToTest GovernorBuildingCompleted

Condition not SettlementBuildingFinished = farms+2
and AdviseBuild = farms+2

Affects BadFarmer 1 Chance 100
;------------------------------------------
Trigger governing6c
WhenToTest GovernorBuildingCompleted

Condition not SettlementBuildingFinished = farms+3
and AdviseBuild = farms+3

Affects BadFarmer 1 Chance 100
;------------------------------------------
Trigger governing6d
WhenToTest GovernorBuildingCompleted

Condition not SettlementBuildingFinished = farms+4
and AdviseBuild = farms+4

Affects BadFarmer 1 Chance 100

Do the same sort of change with BadTrader's trigger as well.

It seems almost pure chance whether the Advisor will recommend that you build an available farm building out of the possible buildings available to queue, although at least it doesn't recommend you build a farm that simply isn't available. If you don't follow its advice then you're guaranteed you'll be stung, at best you'll just negate one of your hard earned GoodFarmer points, at worst you'll now have an active BadFarmer trait.

In the quick test game I ran just now I avoided farms and built 7 non-farm buildings before I got the BadFarmer trait which sounds about fair to me, but it'd be worthwhile having this tested some more if anybody cares to try as well.