A tough start to their pre-season campaign saw Blues go down 3-0 in Crayford, on Thursday.
Adam Flint included two trialists in an 18 man squad, with several players including Jamie Cureton on holiday, and the visitors struggled against a side who already had two games under their belt.
The hosts took the lead through Gaggin in the eighth minute and wrapped up the win with strikes from McDonald (75) and Odusanya (90).
Blues: Mason, Brassington, Cruse, Wright, Green, Robinson (c), Farah, Renee, Osadebe, Ronto, Charles Subs: Crowther, Mason, Thomas, Bennett, Mutimor, Trialist, Trialist
Flint’s team return to action on Saturday afternoon when Dagenham & Redbridge bring their first team to the ProKit (UK) Stadium. Kick-off is 3pm, with prices reduced to £6 for adults and £4 for concessions. Accompanied under-12s are free.