As for the main topic of this discussion:
I agree that to date it's far to profitable for Germany to go with option c), no pact at all. No negatives here, and the ability to annex Poland completely.
However, a dissent hit at the time of the RM pact proposal is not really historically accurate. We all know, with 20/20 hindsight, that Germany entered the pact to get it's hands free on the western front, to deal with France (not the UK, btw., as Germany did't really want nor sought war with the UK). Only problem is, at the time of the pact signing, Hitler had behaved reasonably peacefull. We now know that he pushed for territory in the Sudeten area, hoping that the allies would refuse so he could declare war, but that didn't happen. In the eyes of allies, Hitler responded positively to diplomacy and negotiations.
Ok. He canceled the treaty of Versailles, but only France saw that as a big problem (as France was, of course, the recipient of German war reparations payments which had now stopped

). He annexed Austria, but the allies didn't see that as a big problem. Same goes for the annexation of the Sudetenland (treaty of Munich), and even to a lesser extent with the annexation of Tcech and puppeting of Slovakia.
Not signing a pact with Stalin should cause problems
if war breaks out. Then, when facing a possible two front war, the dissent should rise or other nasty things should happen.
One could also turn it around, and have good things happen to Germany and the USSR if both agree to sign the historical pact. After all, both Hitler and Stalin benefitted tremendously from the pact. It gave Hitler free hand to actively pursue the war option, and bought valueble time for both sides to prepare for the German - USSR war, of which both Hitler and Stalin assumed would be inevitable. Both just didn't want it in 1939. Hitler, because he wanted to deal with the western front first, and Stalin because he needed time to rebuild and prepare the Red Army. IRL, the sovjets supplied Germany with lots of raw materials. In fact, the last sovjet shipment railed to Germany just 1 day before the start of Barbarossa. Stalin kept to the letter of the pact in spite of countless warnings that Barbarossa was imminent.
In the original design there is evidence of an attempt to hit Germany with a negative in case of annexation of Poland without a (partial) pact, which is USSR event 2650. However, this event is inactive and will currently never be triggered.
If the current solution, to hit Germany with dissent when going with option c) in the RM pact event to represent the risk of two front war, then that dissent should be lowered again when France is defeated and Germany installs the Vichy regime. With the defeat of France, the big risk of a two front war is (largely) gone. Same goes the other way around. If the USSR is taken out of the war first (bitter peace event), dissent should be lowered again.
Jan Peter