Killie kid Wales scored his first goal at this level before Bonnar sealed the win in Murcia late on.
Manchester City starlet Emilio Lawrence was denied on three separate occasions and Scotland could have clinched an even more convincing win, although they had to rely on sub Dundee United keeper Ruaridh Adams saving a late Irish penalty.
Boss Gemmill said: “It was good to see the new players and give them the opportunity and give them the experience.
“It was important for them to experience this level as Ireland are a good team.
“David Watson was very influential for us too. It’s definitely optimistic for the future.”
Gemmill handed starting debuts to Lawrence, Celtic's Colby Donovan, Hibs keeper Murray Johnson, Hearts defender Adam Forrester and Dundee’s Luke Graham. Dunfermline defender Jeremiah Mullen was handed the captain's armband for the first time.
Five minutes in, after excellent work down the left, Lawrence squared for Wales to bundle home under pressure.
It was nearly two a couple of minutes later. Wales got to the ball ahead of Ireland’s Spurs keeper Aaron Macguire but had to go wide and his cross was just too high for Daniel Kelly who headed wide.
Millwall midfielder Kelly then tested Macguire with a low drive from the edge of the box.
Lawrence showed lovely skill to...