Just like most hybrid on road cars run some sort of Kers system, in the off road world there will be a hydraulic generator harvesting suspension movement. Maybe sooner than you think
Patents don't have a fair use provision like copyright. The letter of the law is that you are not allowed to make the item even for personal use.
Are you sure on this? I believe, in the US at least, you can make anything you want for personal use, you just can’t sell it.
Yet, the Chinese do this every day of the year 24/7/365 without harm.