> there must be a way to prohibit the commercial use of the hardware designs

Prohibiting commercial use would be incompatible with the open source hardware concept:

https://www.oshwa.org/faq/#noncommercial

> while still allowing other parties the ability to produce and sell the motherboards
> and other components needed to assemble the proposed laptop, or completed
> laptops, at cost, or with a predetermined small profit amount added on.

Who would be such party? I doubt there's any company willing to manufacture the hardware, or pre-finance its production, when commercialization is prohibited or restricted.
Even if this fundraising campaign succeeds throughout its final phase, it won't be easy to find anyone willing and able to manufacture this niche hardware, or pre-finance its production, even with full commercialization allowed, so the license should be as unrestricted as possible.

> the designs should not be just given to anyone without any restrictions

Should the Power Progress Community adopt this stance, then good luck to them finding an interested party.

> so that the manufacturer can make all the profits, without having to pay for
> any of the design costs.

At that point, the design costs will already have been paid for. After all, that's the purpose of this fundraising campaign.