Softener and Softener Dispensers
On the "Fluffy" softener bottles I use, I have noted the usage instructions suggest adding regular dosage to the cap, then topping off with warm or hot water. Add your dosage to the dispenser (which should only be HALF what is recommended), then top the rest off with Hot water, which should at least prevent the gummy stuff building up - especially as Pierre's machine has such a short cycle.
And Pierre, I do doubt the effectiveness of having a warm rinse for softeners in your instance (especially with such low water levels and your long pipe runs). I think it just boils down to how they formulate your preferred brand of softener, and the way in which you dose the softener.
The other issue is that of dispensing the softener in the first rinse, which would negate its usage. Especially since it would be rinsed away, but as "Launderess" has pointed out, the waxy properties of the stuff could cause dirt and grime to cling back onto the clothes instead of being washed away. (Scary!)
But do experiment - try finding a less concentrated brand of softener that suits your sensory palette that is nice and runny, and water it down. Remember to clean the siphon out with pipe-cleaners regularly to stop waxy or mouldy buildup in the dark, moist places down there (that also get warm with Hot/Warm washes).
Goodluck!