Wow, that is really cool. I like the videos, and I think your project is very creative.
I plan on playing Mario Builder again one day, but I didn't really find time for that.

Seriously, though. Mario Builder doesn't really look all that good. The Field of View is nice, and it feels like an SMB3 FOV, which I like, but the engine is
Shit!
The physics are very awkward
(Though it's not like SMBX can do any better...)
The flashing and walking animations feel weird, and It tends to lag on my computer.
So... I'm gonna stick to SMBX. It's more polished.
Don't get me wrong though. I love your thing that you're doing!! It's great!!
I hope it goes well!!
EDIT:
Actually, I still am quite jealous...
I do wish SMBX had:
A real Goal Pole
Invincibility Star
A built-in Timer without the use of LunaDLL
The modern Damage cycle - i.e. You have a fire flower and you get hit you instantly Shrink to Small Mario Instead of turning into Super Mario.
Though I don't think programming all that stuff into SMBX is possible. (And if it was, It would probably take forever unless you are really good at it.)