For solo home use, your best fat assessment device might be...the mirror. Done properly, the calipers are a reasonable proxy for expensive professional tests. But the slightest error in using them can produce wildly variant results. The impedance monitor scales are high on precision but low on accuracy; your level of hydration, time of day, and other factors unrelated to fat have big impacts on the number you get and the underlying algorithms are not perfect. The mirror promises less precision (no two-decimal fat percentage estimates from this one), but the visual inspection is more stable, too. Keep in mind over time that as we age we tend to accumulate more internal fat, around organs as opposed to just under the skin, so even if you look exactly the same in the mirror in 10 years you're fat percentage has probably risen a bit.
If you want a precise and accurate number, there isn't really a good home-based substitute for hydrostatic testing. You could get one and then use your impedance monitor to measure change over time, so long as you're minimizing variability in measurement conditions (e.g. doing it every morning after getting out of bed but before eating) and not getting too caught up in short-term day-to-day changes.