As for the quality of those few images is concerned, one painting, Illusions, is in the Smithsonian American Art Museum collection. Another, his portrait of Ebba Bohm (c.1905) was on display at San Francisco's De Young when I visited in December.
The Ebba Bohm portrait is interesting in part due to its comparative "flatness" -- not poster-like, but far from the rounded, hard-edge academic style that was prevalent only a few decades before Fuller painted Ebba. This characteristic is not so apparent in the images posted here, but for some reason stood out when I viewed the painting in person. I found it a very satisfying work by a not-well-known painter.