Personally, I wouldn't use empty fields as the next developer who comes along will instinctively wonder "why are there empty fields here?". It's not very elegant.
Here is an OOTB method using CSS that you can do in 10s.
On your fields, add the following property:
wrapperClass -- String -- padding-b-2
padding-b-2 is an OOTB utility class, so no need to add your own CSS. wrapperClass will add that class name to the wrapper element.
You could also use the granite:class property with the same value, but it's best to use wrapperClass as a general rule. This is because granite:class adds a class to the actual input and wrapperClass adds a class to the wrapper which contains the input and the label. For bottom padding it makes no difference but you can image that for top padding, if you use granite:class, you'd have padding between the input and label, and nobody wants that 😛
This comes with a warning: these utility classes are only usable specifically in dialogs of the Page Editor. If you want to use the same trick somewhere else in the TouchUI, you may have to find another way.