The forward opened the scoring with a quickfire brace inside five minutes to put the visiting team in complete control.
Watson then added his third with just a minute to go, to make it an impressive 17 for the season, as he is clear at the top of the leading marksmen charts.
The result also means Kempston now sit third in the table, four points behind leaders Royston Town with a game in hand, although they are without a game this weekend.
Rovers: Conway, Guiney, Herbert, Goodman, Fryer, Macrae, Fuller, Shepherd, Marsala, Watson, Johnson.
Subs: Sundire, Riley, Ivy, Simpson, Stoyles.
Kempston Rovers Development side were 5-1 winners over Stevington in their Beds County League Premier Division clash at the weekend.
Michael Fisher, Samuel Smith, Ed Wheatley, Patrick Asare and Jakub Buris all netted in what was the side’s first victory of the campaign.
They visit Sharnbrook this weekend.
Meanwhile, goalkeeper Carl Knox and midfielders Kye Andrews and Harlem Sambu were expected to join United Counties League side Cogenhoe United on dual registration to gain fitness.
The club have also advertised for a qualified goalkeeper coach to join their senior management team.
The individual will have the relevant experiences as a goalkeeper and a passion for development and coaching, working with the U18, development and first team goalkeepers at the club’s training facility while supporting the first team squad on match days.
Email joint boss Jimmy Stoyles at [email protected] for details.