Cosmic_jumper and I had many exchanges over the HiT clutch.
I don't have the luxury to try different spring combinations. Taking off the sidecar is a major undertaking.
Now after the experience of Tim I'm ready. But one perhaps crucial question came to my mind=

How much torque, if that is the correct word, do you need to pull off 1200lbs on a very steep hill?
Why 2500 rpm?
The Hit can be tuned so it locks at 2500. Which I thought is ideal for going slow on very steep rubble roads.
Suddenly it occurred to me that 2500 may be good enough to keep the vehicle moving but is also enough rpm power to pull the bike from standstill ?
Is there a rule of thumb how much power has to come to the wheel in order to move 1200lbs plus factor x for the extra load/ hill.

Perhaps the locking of the Hit should be set at higher than 2500 rpm.
It would be rather awkward to have 125cc Honda Waves 2 cute Thai girls plus children ( reality) overtaking my spacecraft ( by Thai standards)
I hope my layman's word make some sense.

Pico

I'm going to go out on a limb here; all things being equal, if the HiT Clutch (or any centrifical clutch) is set up to engage at X rpm, adding a heavier load would result in the clutch to slip more --until the inertia is overcome.

That the HiT Clutch is engineered to lock up at Y rpm makes me think that one of two things will happen. One, the clutch will continue to slip somewhat. Or two, the clutch will try to engage (lock), then release, then lock again i.e. the clutch will chatter. If that's the case the clutch is actually trying to get the scoot to wheelie --but given the weight of the scoot, sidecar & load, that will never happen.

Sorry I can be more reassuring, but I'm not an engineer, and your sidecar outfit and road conditions are so rare that it's difficult to imagine solutions.

FWIW; When sidecar outfits are added to geared motorcycles the chain sprockets are usually changed too to lower the gear ratios.

You seem to be 'between a rock and a hard place'. The only thing you can do is go with your best guess. Light Clutch and light Pillow springs work best for my set up.

Thanks Tim, question remains are 2500 rpm enough to pull 1200lbs plus factor x ( steep incline)

Also understand that while the engine puts out 50 hp, you only get about 37 at the rear wheel. Other mods, such as an exhaust change and power commander can add about 5-6 horsepower to what you can use.