yes, even though it will be in a smaller area, the heat pad should be able to still provide good basking temps at night, although they don't "need" those temps at night but it is still nice for them to have that option. that's one of the great things about having a larger cage is the inhabitants can choose whatever temp and humidity they want. the two geckos in my house live in a 20l with 4 different hides, one directly under a 50w heat bulb, another one opposite side, a humid hide next to the hot one and a fourth hide in the middle. if you have a heat pad(get a controller for it no matter what, i didn't and my geckos got burned) or a heat lamp put it on one side only, then if it's 72* in your house then one side of the terrarium might only be 72* and the other might be 86* and the geckos can thermo regulate based on their own needs, another disadvantage to a small cage is that they can't do this.