Actually Go-cart shocks would be very good. The ones I had seen online were a little long, but there might be more suitable ones out there.

As for forks, that crossed my mind, but yes, too bulky. I had considered using 16" rigid forks oriented horizontally, combined with a regular shock. Overkill I concluded. I can make the chassis parts myself, it's only the suspension that leaves me at a loss.

Thanks. I think I'll pursue the go-cart shocks. Never having seen a go-cart I had no preconceived idea.