I can understand wanting to turn off the damn stop/start system. We recently had a road trip in the USA and hired a Dodge Durango with auto stop/start. We started in a quite warm Los Angeles and everytime the car stopped so did the AC. If you were at traffic lights for more than a minute the AC actually started blowing hot.
From my understanding the stop/start was more to do with emissions than economy, the government not wanting lots of cars standing at lights spewing out exhaust fumes. so they could get their figures down.
One method I thought of was a semi permanent fix. A small circuit board connected to the rear of stop/start switch, with a 555 timer on it so that it could activate the switch everytime you go in the car, or a small relay.