Gracie Bon Doubles Down on Wanting More Seat Options for Big Booty Flyers

Gracie Bon's leading the charge for big booty travelers everywhere ... asking for more accessible seating while 30,000 feet in the air -- doubling down on her plea from earlier.

We talked to the Instagram model on "TMZ Live" Friday ... and she absolutely torched the seat sizes on airlines as they currently exist, explaining she's comfy on trains and automobiles -- but there's barely any room for her on planes. Yes, it's a real problem ... so says GB!

As explained to us here, Gracie hasn't seen any airlines offering options to bigger people ... and she suggests putting a couple extra large seats on each plane exactly for people with a bit more junk in the trunk.

Gracie says she needed two economy seats to fly to Rome, where she called us to do the interview ... and even that wasn't comfortable for her. Check out the vid -- she's clearly doing her best, but the makeshift bench ain't supporting her big behind, the way she needs.

Harvey and Charles also asked asked Bon about some rumors/assumptions that she's had butt implants ... making the size of her caboose her choice, but Gracie set the record straight. She said she's never enhanced her ass -- instead, she just downsized the rest of her bod.

As Gracie tells it, she used to weigh 300 pounds, but she got surgeries to manage her weight in her belly and arms, so she looks small up top. When it comes to her thighs and butt though ... the good docs left all that intact.

Now, she's not hating on girls who've gotten surgery though ... saying the airlines should accommodate every passenger they can to give people of all body types the same experience.

Bon's opened up about her body to us a lot in recent days. We spoke with Gracie Thursday too, and she told us pretty much the same thing -- adding she's serious about petitioning airlines for more equitable accommodations.