Hello,
Sorry yes I know you posted this question before, I didn't mean to ignore you, I've been thinking about it.
It is definitely something I'm going to consider for the next release, in fact you can already do it (sort of)...
What I mean is that if you have a project file that is configured for 16x16 tiles, CharPad should load it and let you use/edit it, you just can't currently create such a project in CharPad, so it's probably not very useful to you!
(hex editing an existing project's tile dimensions can be done very easily but you would still need the file size to be correct, it could be done).
I have added your request to the todo list and will do some tests very soon.
Thanks for the suggestion!