For 1:1 scaling, you could split the map into sectors and print individual sectors on e.g A4. And afterwards, assemble the map like a puzzle. 
Just like big billboards are. They aren’t printed on a 10m x 5m paper in one go. They are printed on smaller pieces and then assembled to get one, big picture.
Well yes, I could puzzle the pieces together. But the total map mustn’t be too big, because where would I put it. I am also thinking of a foldable map as one possibility. But I’d rather have one hanging on the wall like a collectable. Call me crazy. 
The digital map is easier for quick reference. I load the map in my graphics program, because I haven’t found a simple and free picture viewer that zooms close to the 1:1 scale. Google drive works, but zooms not nearly to 1:1 scale, Microsoft Photo’s is better that way, but doesn’t allow vertical and horizontal movement with the mouse. Go figure.
I have time. The print shops aren’t open here yet, so I have to wait anyway to see what is possible. But I also like the new island to be included. So there’d that too.
I’m using freeware software called: IrfanView (v 4.51) and it zooms-in way past 1:1 scale. I can even see individual pixels, when needed.
Just tested in my InfranView and when holding down right mouse button, i can pan the image where-ever direction i want it.
Give it a check. 
Ok, that works great. I had to install the plugins too. I especially liked that with left mouse button held you select a part of the map and then click that part to zoom out on that selection. Very quick.
I’ve been using IrfanView since my WinXP days. 
Still works great, all these years later. 
If I don’t forget, I’ll give it a go on our printer. Wanted to see what it looks like when scaled to fit within 1200 mm width. Should be good to print on banner material I guess.
O cool, I’m curious what the result will be.
I have Canon photo printer and i can print on high-end professional studio finish photo paper, size A4, but i haven’t bought that expensive paper for my printer. 20 sheets is €94. 
So far, i’ve printed the standard photos, 10x15cm, among other things.
I did notice a slight quality loss when zooming in with IrfanView compared to my graphics editor. Also the colors seem harder. But still very good to use.
Found a free graphics editor on my PC called “Paint 3D”, which also zooms all the way to pixel level. Not sure if that is installed with Window 10 though. I certainly did not install it.
By the way, do you know if there exists a completely clear world map, with no icons on it at all? Would be interesting to get it into vector format with all the icons and text…
I think there is a clear map, because Artur Meinild used such a map with his online coordinates map. I don’t know how to get it. Edit: O wait I do. Send you an email.
Following up up a question about the colors / looks of the map. I added a adjustment layer and adjusted the color balance. This is just an example.
original:
Adjusted
Any progress on your printing adventure?
The printer’s been quite busy, and will be for the next few weeks, so not yet sorry to say.
Super cool, man! Now all we need is a pronunciation guide. Lol
If I get the time, and with Gysbert’s permission, I could maybe make a version with my coordinates overlaying Gysbert’s labelled maps. Or if anyone wants to use my HTML source, please do so. 
Oh, and a suggestion: Maybe remove the rivals? They’re not really useful in the long term, or for anyone else for that matter.
I am ok with it. 
Thanks Kalle. You have fun with it.