Townsend admitted “it probably wasn’t as free-flowing a game as we’ve had on tour” but was full of praise for Van der Merwe.
“He didn’t get as many touches, but he finished his try well,” he said. “We’re all delighted for him and it’s an amazing achievement in such a short space of time and now he can kick on and score more tries in the future.”
Both sides went into the game short of full strength, with Scotland fielding a side almost exclusively made up of Edinburgh and Glasgow Warriors players, while the hosts were missing some key performers who are in their Olympics Sevens squad.
It was Uruguay, smarting from last weekend’s heavy loss to Argentina, who came out the blocks faster.
They should have made early pressure tell, but fly-half Etcheverry pushed his penalty wide from an inviting position.
The Scots made them pay almost immediately, after Ben Healy’s monster kick from his own 22 took his side deep into the home half.
With his second touch from the resulting rolling maul, Ashman dived over and Healy added the extras off the tee.
Uruguay suffered a quickfire triple blow as Juan Bautista Hontou was forced out of the game with a knee injury, Diego Arbelo was sent to the sin bin and Matt Fagerson put flanker Crosbie through for Scotland’s second try.
Healy knocked over a simple conversion and Van der Merwe was soon touching down in the corner for his record-breaking try – the winger moving one ahead of Stuart Hogg after just 41 caps.
A loose Healy pass helped Uruguay back into the game as Alvarez cruised in under the posts before Etcheverry went over from close range and added his second conversion to make the score 19-14 at the break.
Diana burrowed over to draw the hosts level and only the latest of a series of missed kicks from Etcheverry prevented Uruguay taking a surprise lead.
That spurred Scotland into action and on the back of rolling mauls Harrison, with his first international try in his second appearance, and Schoeman went over and Healy added the conversions to restore their advantage.
That was enough to ensure Townsend’s side added to previous tour victories against Canada, United States and Chile at the end of a long season against a side who have now lost six of their latest seven outings.
Uruguay: I Alvarez, Bautista Hontou, Alonso, Inciarte, Freitas, Etcheverry, S Alvarez, Peculo, Pujadas, Arbelo, Aliaga, Leindekar Virginio, Ardao, Bianchi, Deus.
Replacements: Gini for Bautista Hontou (20). Not Used: Myszka, Sanguinetti, Piussi, Magno, Civetta, Diana, Suarez. Sin Bin: Arbelo (23).
Scotland: Paterson, Rowe, Jones, McDowall, Van Der Merwe, Healy, Horne, Sutherland, Ashman, Sebastian, Williamson, G. Brown, Crosbie, Darge, M. Fagerson.
Replacements: Steyn for Rowe (54), Hastings for Healy (54), Dobie for Horne (62), Schoeman for Sutherland (54), Harrison for Ashman (62), Walker for Sebastian (54), Johnson for G. Brown (69), Ritchie for Crosbie (62).