Is it possible to construct a form using Freeform/Freeform Pro and submit it using Safecracker? I'm basically just trying to combine the ease of building a form with the ability for it to create a channel entry, with the intention of creating a booking using the rEEservtion add-n.
Freeform saves submitted data in its own table, so it's not saved as a channel entry. Depending on how sophisticated you need your form to be, however, I have accomplished what you're looking for thanks to a great post by Low called User generated forms in EE. What Low explains in the article is that with a bit of planning, and ideally with his free Low Freeform Field add-on along with Matrix, you can create forms with channel entries. He only takes it so far in the post - but I can tell you that I have taken it further by hooking in jQuery validation, as well as used the Freeform Templates add-on to make the experience even simpler. If you plan it out and get a bit creative, it can be quite powerful. It will never be the easy drag and drop to create a form system that Freeform Pro, Forms or Proform are, nor can you easily do conditional field triggers, but for straight forward applications, it can put a lot of power in the editor's hands. I'd recommend you read through Low's post and see if you can come up with creative ways to extend his example to possible suit your purpose.
Quick caveat - I haven't tried this approach in a little while so I don't know how recent a version of EE the approach would be compatible with. I don't have any reason to believe it wouldn't work with the latest version of either add-on and EE 2.5.5, but I've certainly never tried it with 2.6.1.