ffkiwi

Seeing nothing so far offered seems to meet Sport Pilots requirements-I suggest you go trawling in the MB or MAN archives for the 80's-Bill Cannon-the 'Cannon R/C' guy had two designs published for the G-Mark 03 and 061 engines he distributed in the USA-and of course he sold the micro R/C gear to go with them. My memory is a bit vague on detail-but they may even have been the same design at two different sizes.
As I recall it was a low wing full house 4-channel aerobatic design-which should satisfy sport pilots need for performance. The G-Mark 03 Humming Bird engine was slightly larger in size and displacement that the TD 020-but of similar power (the TD would probably have a slight edge!)
Built light-and with modern gear, this should perform well.............

I'm only about a week away from departing for the FF World champs, so have no intention of trawling through dozens of back issues of MB or MAN to find the specific article and plan. My gut instinct is that it was in Model Builder not MAN-but I could be wrong. Someone here will recall the name of the design, and the appropriate issue. then its over to Sport Pilot if he likes what he sees. I don't know what the current status of the MB plans service is-Bill Northrop died a couple of years back. I'd just be inclined to scan the plan from the mag and have it enlarged by a copy shop to the correct size.

Another option would be any of the Ace R/C 1/2A pattern ships scaled down to about 30", or the 'Eyelash' ditto (which was a MAN plan)

ChrisM
'ffkiwi'