BODYDROPPED MAZDA BEDS?

I AM IN THE PROCESS ON BODYDROPPING MY BED MY FLOR HAS BEEN CUT OUT ALL THE WAY UP TO THE RAIL TO MAKE ROOM FOR MY RIMS AND NOTCH, SO I AM DOING THE BODYDROP IN 2 SECTIONS I HAVE THE SMALL FROM PEICE DONE, BUT NOW I AM ON THE REAR I CUT THE SIDES OUT AND DOWN THE BACK BY THE TAIL LIGHT AND ACROSS THE FLOOR, NOW ON THE REAR TOWARD THE TAILGATE, I HAVE A SKIN ON IT SO I CAN'T OPEN THE GATE, THERE ARE LIKE 4 SUPPORTS UNDER THE BED I WAS CURIOUS HOW YOU GUYS CUT THROUGH THEM? DID YOU DO IT FROM UNDER NEATH OR USE A SAWZALL? THATS THE ONLY PART OF MY QUESTION I NEED HELP TO I HAVE ALL THE REST DONE JUST THAT BACK PEICE BY THE GATE. I AM CUTTING ON THE FLOOR BEHIND THE SEAM WHERE THE 2 PEICES MEET RIGHT ALON GTHAT SEAM.