No, sorry. I tried those settings and even turned off aaRealisticFatigue.encumbMult completely. Yet while standing perfectly still with less than half my encumbrance limit I'm already losing fatigue. As far as I'm concerned, I should be able to get at least up to half my limit before I start losing anything. SM Encumbrance doesn't start kicking in until I've reached the game's default encumbrance level then I start losing fatigue. Up until that point it's business as usual, unless I'm running. That's just how I would like it to be. I also like SM Encumbrance's Fallout style options. It's certainly a bonus that your mod works on all creatures in the game and not just the player, but I prefer the way SM Encumbrance works on my own character.
The fActorStrengthEncumbranceMult and encumbMult settings I mentioned adjust the max encumbrance and fatigue burn rates. The effect you are describing is the fatigue encumbrance drain that reduces max fatigue for high encumbrance. There is another similar fatigue health drain that reduces max fatigue for low health. These two effects are not prompted for in the OMOD install script, but can be adjusted by editing RealisticFatigue.ini and changing encumbDrainGain and healthDrainGain. Set them to 0.0 to turn these effects off.
RF uses fatigue to represent the mount of unfatigued muscles available for running/jumping/attacking. The fatigue encumbrance drain effect represents the fraction of your muscles that cannot be applied to running/jumping/attacking because they are preoccupied with lifting. No matter how rested you are, you cannot attack as effectively while you are busy lifting 50Kg+ worth of stuff. Similarly, the fatigue health drain represents the fraction of your muscles that cannot be applied to running/jumping/attacking because they are damaged. These effects are applied using a non-linear x^2 curve, so at 50% encumbrance your fatigue is drained 25%, but at 30% encumbrance your fatigue is only drained 9%.
Note that "half your encumbrance" equates to half of your maximum lift. RH with default settings assumes that a starting character with 40 strength can lift 80Kg max, so 50% encumbrance would be 40Kg, which is nearly 10Kg more than the strongest/fittest soldiers in history have ever worn into combat.