Donald, roll paper used to come in 6' widths for colour negative, from Kodak.

B&W Ilford multigrade was produced to 4' wide and their RT machines were 4'3" wide (I think).

I'm not sure whether you will find the same roll paper today, but transporting was a problem, especially if it travelled overseas. The containers for the paper looked like small lead coffins and cost a packet.

As for a shutter requirement for an enlarger that can cover 10x10" I have used shuttered and shutterless enlargers.

All of the shutterless 10x10" enlargers seemed to have the same type of output; two banks of 4 x 250W enlarging globes for a given output of 2,000W. The downside if you are enlarging colour, is that if a globe blows, then you have to change all 8 globes.

With B&W you can sort of get away with replacing the blown globe, but you then end up with uneven illumination, personal experience here!

I think AA's enlarger had 36 light globes for extreme illumination consistency.

One thing most copy cameras have is a light sensor stabiliser. This measures the amount of light given and turns off the lights when the required level of light has been received. Adapting one of these sensor units to a copy camera enlarger would virtually alleviate a shutter requirement and/or a timer.