I wonder if it could be worthwhile making a motherboard replacement for an existing common laptop, so all you need to do is buy an old dead version of that laptop (I'm thinking the flood of popular but flawed late model iBook G3s, so many of which have dead logic boards and can be picked up as non-working shells easily enough) and fit a replacement Amiga motherboard inside - one designed specifically to fit the form factor. Combine that with a pre-made top shell replacement to add whatever logo you'd like instead of the Apple, some Amiga specific keycaps for a few of the keys on the keyboard and *bing* - one Amiga laptop.
Of course, I know absolutely nothing about PCB design, or how easy/difficult it would be to make a laptop form compared to a desktop - but picking up a dead iBook for a couple $hundred gives you a decent screen, case, keyboard, optical & hard drives for less than the value of new component parts.
