Aside from the belt load which may not return enough to bother with long term because you WILL need electric power at some point. The simplest solution that is non-invasive is to supply power to the electrical system from another power source i.e. solar panels and an additional power regulator from another battery. If the car battery is supplied current that keeps it about the 14.x voltage the alternator will stay "off" and not load the engine and the car battery stays fully charged and will not have it's life shortened by cycling. The additional battery will provide power until you want to regen down hill charge it from the alternator then you just load down the system and charge the extra battery or charge it from the solar and/or grid when you stop and park. This will also allow you to run accessories longer without the engine running like when you are coasting with the engine off while maintaining full system voltage for brighter headlights.