In maintaining the position existence has no intrinsic meaning, my inclination is to focus on those things which are undeniably provable. Unlike many philosophers, for example, I'm disinclined to deny my very existence.
However, given perspectivism, there's alarmingly little that is provable beyond existence itself. For example, individuals might make seemingly obvious observations such as, "The grass is green," and maintain that as some sort of absolute truth, but it isn't. Those who are visually monochromatic might accept this assertion as truth because they have no reason to contradict the observations of the majority, but the very nature of monochromatism renders that supposed truth incapable of being the truth for them.
Similarly, those with advanced macular degeneration perhaps no longer experience grass as something to be experienced in the visual sense and only, 'Observe,' it with tactility.