Try Epson 2100 (2200 in the USA).
The 2100 comes with a roll paper holder but I don't use it because of paper
curl.
I used "Panorama Factory" from "Smoky City Design" to make panoramas and
set up a custom paper size in the printer driver. The largest I've done was
on two sheets of A3 paper joined together to make a sheet 8420 x 2970 mm.
There are limitations on the max paper size that Windows can print on
(regardless of printer) but I haven't hit them yet.
I think I read there was also be a 4G Pixel (or was that a 4G Byte) image
size in Windows?
The 2100 will print borderless so you can always join up sheets to get above
the Windows limit.