I had a very long discussion with the guy behind the design of this bike:
...the Pinnacle Tharpu Peak, similar design to several others. He thought that the best suspension designs kept the shock travel in-line with the suspension compression. There are an awful lot of other considerations, which is why Linkage is superb for playing with ideas:
When the Specialized patent over the four-bar or Horst link design lapsed, he expected more companies to adopt it - it's a convenient way to prevent the single-pivot arc problem of shortening the wheelbase as the suspension compresses. The shape the rear axle describes as it moves through its travel is important.
I like the idea of playing with suspension designs, but I have never really tried it, only spoken to a few people who have. I think I'd probably spend some time analysing what other people have come up with, and the strengths and weaknesses of their designs, before trying to come up with my own. And I'd probably look at downhill bike designs too, there have been some crazy bikes put together in the name of long travel, smooth travel or optimal axle path.
I'd be concerned that a 'one-legged' rear suspension design would have to be heavily reinforced to prevent the bike twisting under load, both suspension-compressing load and the forces of pedalling. 'One legged' motorbike rear arms are hugely strong; this isn't a problem when you can just fit a bigger engine, but it might present weight issues on a bicycle.
Anyway, good luck!