To avoid self-dealing, include the value of the laptop as part of the trustee’s compensation (and report it for tax purposes). The foundation may even “gross up” the trustee’s compensation to account for the income taxes the trustee would have to pay.
If the laptop were used for foundation business 40 hours per week, you might be able to consider the personal usage as a de minimis fringe benefit, and not report the laptop’s value as compensation. But given that trustees are likely to use it for much less than that, it is harder to make that argument.
For more on self-dealing, see our publication How to Avoid Self-Dealing, or consider becoming a SignaturePLUS member, which includes up to 10 hours of legal guidance from carefully chosen lawyers.