Watson and Toole ran back-to-back singles off bowler Akash Gill to see their side past Wanganui's total, with the innings closing ten runs later at 281.
In reply, Wanganui were defiant with their best innings in two seasons, reaching 259-5 in 61 overs by the close of play, on the back of two brilliant centuries by Smith (102 from 101 balls) and a stunning return to form for Mark Fraser (103 not out).
They will be the first names added to the Wanganui Honour Board for a batting performance since current Manawatu player Henry Collier's century in 2014.
The Wanganui Chronicle will have full scorecards and reactions tomorrow.
Scoreboard
Wanganui first innings: 270 (B Smith 61, D Rayner 41, R Kinnerley 36, S Badger 29, M Fraser 24; R Toole 6-72, T Kuggelelijn 2-52).
Manawatu first innings: 281 (L McHardy 83, D Meiring 56, B Small 33, T Kuggelelijn 22, H Collier 20; R Kinnerley 3-59, C O'Leary 2-34, A Gill 2-71).
Wanganui second innings 259-5 (M Fraser 103no, B Smith 102, S Badger 23).
Result: Manawatu win on first innings points.