That's effectively what the Lunacy Challenge is, except it is for
13 rides of an arbitrary distance. You are welcome to switch to that.
With the COVID situation getting worse I have decided to drop out of this year's '50' challenge and focus on getting the best possible Lunacy Challenge result later in the year if/when longer rides become less of an issue.
Until then I will stick to doing local rides of no more than an hour to get some fresh air and will do harder sessions on my turbo trainer to get fit.
Stay healthy everyone and (hopefully!) see you for the 2021 Half Century Challenge.