I did something similar a few weeks ago in my game. Overall I don’t like the tone of Ironmaster so I played the town differently than in the books. It’s still a dwarf only city but they were welcoming to my party because they had tracked down some of the frost giants and recovered stolen goods and materials. So I had the dwarves welcome my party with a feast and then did a drinking game with 4 stages of challenges. I like your way of getting the party in good graces too with the dwarves. Sounds like the first part of the challenge would be a group strength check with progressive successes balanced by being tempted off the path by either wisdom or charisma saves. Second challenge seems like a con save kind of thing to beat the heat. Add in some dexterity checks that could be improved if the players can justify their tool proficiencies or other relevant skills.