Glamorgan amassed 547 with Michael Hogan striking a half-century during a breezy last wicket stand of 95 in 11.3 overs with Timm van der Gugten.
Hogan's 54 came from 47 balls with 7 fours and 2 sixes, and propelled Glamorgan to their second highest total of the season.
"We had a bit of licence given we had maximum batting points, so Timmy and I went out and had a bit of fun," said Hogan. "I don't think they bowled particularly smart to us but I managed to hit a couple out of the middle.
"With the weather, being nearly 340 in front (on first innings) leaves us in a good position to bowl them out without having to bat again, it's nice to contribute with the bat, finally, but there's still a lot of work to do.
"There was still a bit of nibble with the ball, so if we can nick a few off early we might be able to break their backs. It's a lot better (for batting) than day one, but there's still a bit of life in the pitch for us."