And if rented as FURNISHED... then you are valuing a small hotel...not a house. Part of the RENT from VRBO is due to the furnishings. Part of the RENT is spent on the clean up after the occupant leaves. Part of the RENT is paid to VRBO. Part of the RENT is spent on management. Part of the RENT is spent for utilities.
So, to use a VBRO income legitimately, you must build a Net Operating Income statement. Then do the same for comparables and calculate the direct capitalization rate. You do not use GIM's.
Do the cost approach (it's new.) Do the sales approach. Consider if there is an additional DEDUCTION for functional obsolescence - for being a super-adequacy. Actually, here where I work we do have a few such buildings that are 4,000 SF or more. And several that are about 50/50 shop and house, that might be closer to 6,000 SF.