Solar Fryby
A hot option would be a solar-sail launched on a solar fryby launch trajectory. That could test out techniques for launching future interstellar sails at up to 0.01c. To get to the grav-focus at 550 AU in 20 years would need a transit speed of 27.5 AU/yr or 130 km/s, which is pretty low performance for a high-end star-sail - in otherwords doable by current materials, not diamondoid quarter-wave sails that'll be needed for 1500-3000 km/s.