I would just stick some long bent bolts in the holes and take them out after the test!
Or go to a tester who is less strict about the dafter regulations!
Enduro bikes have long seats but no passenger pegs. If they're going by length of seat it's just ridiculous.
If the seat has the grab strap (passenger grab )fitted it may be seen as a two seater if you don't have a grab strap on the seat it's usually seen as a single seat .