It's the first time I've heard of the MX5 having cooling issues too!
If anything I always felt my MX5 was over-cooled.
If you do want to go with it there's acres of space in that area on the roadster:
Like porkchop says, the inlet side is very busy, and it might be a struggle bringing the hose down that side.
I recon you could easily bring it back on the exhaust side without getting too close to the manifold - I've got a big empty gap that side (just begging to be filled with a turbo!).