I am not saying I have never installed single-piece oversized faces. I have, but sometimes lived to regret it.
I once installed a pair of 6x8 pans in an existing double-sided pole
sign. They were heavy, to be sure, but I man-handled the first one in place. I took the precaution of first thoroughly cleaning the inside lip of the top retainer that was to receive the hanging bar. I even waxed it with a piece of paraffin and then waxed the bottom of the hanging bar as well. The challenge, of course, was hanging onto the face with one hand while controlling the bucket lift with the other. So I attached a rope to the top edge of the plastic using machinist-type center-pull clamps (center-pull clamps don't try to bend the plastic like a regular C-clamp can). I put a rope through the clamps and hooked it over the end of the boom and held it there with one hand while I worked the lift. Once I got a top corner with its hanging bar started, I slid the face in, removing the clamps from the top as I slid the face. Ha, ha, I was invincible!
Unfortunately, the other side did not want to fit at all. The bottom of the cabinet appeared to be a little cantilevered, making the opening on the open side shorter in height. And I think there may have been some sag at the ends, too. In hindsight, perhaps I should have immediately trimmed the bottom edge of the second face, even if it meant going back to the shop, but I didn't. It took the rest of the day to install the face, and I no longer felt invincible.
To get the face into the opening, I put a ratchet strap on the other side of the cabinet to try and pinch the top and bottom together a little on that side, hoping that would spread the open side a little. I don't know if that helped or not, but it wasn't till I loosened the bottom retainer considerably that I was able to get the face started and hanging securely on its hanging bar. I slid the face a ways into the cabinet till it stuck and would go no further. So to get it to slide the rest of the way, I clamped a rope to the leading edge of the face and, leaving a large length of the face extended precariously in the air, positioned myself beyond the opposite end of the
sign and used the rotation function of the boom to gently tug the face sideways into the cabinet with the rope attached to the boom. I was then able to button up the retainers and I quit for the day, exhausted, and went home to sit on the porch.
When I eventually got a call to service the same
sign, I told them I would "have a hard time getting to it" and suggested they call one of the big shops.
Brad
Center pull C-clamp picture attached. Probably not the correct name for the clamp