The Pilgrims prevailed courtesy of an 85th minute strike from the unnamed trialist who also netted a penalty in last week's 3-2 defeat at Basford United.
The majority of Craig Elliott's new-look squad were in action alongside a clutch of trialists and midfielder Grant Roberts, who is continuing his rehabilitation following a long-term knee injury.
Boston (4-3-3): George Willis (Dylan Parkin 46); Trialist G, Ryan Qualter, John McCombe (Ben Middleton 46), Jordan Gough (Ashley Jackson 59); Spencer Harris (Grant Roberts 59), Andi Thanoj (Trialist A 59), Brad Abbott (Trialist H 46); Nathan Arnold (Trialist D 72), Trialist B; Jonathan Wafula.