420 was it for me.
I couldn't fit in my 09 mustang but still could fit in my SUV.
Walking up stairs was very very hard.
Next to impossible to tie my own shoes and very hard to put on socks because my belly was in the way.
Unable to sit in some chairs as well.

Many view things in a black and white perspective and make things more complicated than it needs to be.
What you might perceive as a BBW may not be to someone else.
Simplicity makes life more enjoyable with less stress.

There is no cut and dried chart that I know of as to what weight any of those would be.
Personal opinion is yours and yours alone.

Don't have to it sticks out already

Stop worrying about what other people think.
They don't worry about what you think do they?

Problem with that will she be ok with you doing it?

I think your idea of doing videos you should do that.
Some of us here like weight gain on guys.
99% of weight gain videos are of females so there is a need here for a guy to that.

I have dated both skinny and fat but I like the guy to be bigger than me.

You do realize the "thesis" claim by the OP has been used by many to gain info then share the info in articles in shady publications in Europe.
Used to get those here years ago and they were promptly removed by the mods.

I have gained and lost several times and each time I gained the weight back I got flabbier and fatter in places I was never that fat in the time before.