Would a 7" (diagonal) screen be that much better for viewing than the LCD on the back of a camera?

For instant "proofs" (albeit completely "as is" from the camera - no sharpening etc) how about a little Canon Selphy printer? Just plug the card in, select the shot(s) to print and away it goes. Some can be battery powered (for about 36 shots IIRC) and they are Dye Sub (so no liquid inks to escape...). Probably the ultimate answer is a trolley with a laptop, A4 printer, 12V battery and an inverter - a complete dry room in one convenient package!