You can double this recipe and bake it in a 9x13" baking dish for one hour.
I highly recommend using a digital kitchen scale to measure your mochiko. Differences in the amount of mochiko may result in differences in the thickness of your batter, which will affect bake time.
For this recipe, I suggest avoiding the Trader Joe's brand of coconut milk, which doesn't have any thickeners and can cause the batter to become more watery.
Different brands of ube halaya may be more or less dry, which may also affect your batter texture and bake time. Expect that more wet batters will take longer to bake.