Just been chatting to a mate of mine who had booked to attend. He lives locally and worked with the rugby club to organise a successful rally a few years back and was pretty happy with them. It might be that I owe the club the benefit of the doubt as it appears that cancellation was truly beyond their control. The timing of it could be a different matter though.
One suggestion put forward was the Bull'i'Thorn pub, at Pomeroy, which is only a couple of miles further down the A515 from the rugby club.
They used to host an annual scooter rally until fairly recently but, looking at their website, the situation may have changed. Might be worth asking the question thjough?
https://www.bullithorn.co.uk/camping/
Rob