Yes. The split shift is there. The officially supported "7bit layout" has it.
Down-arrow will have to be a 1.25u key (or shifted 1/8 key to the left).
I do think that the right arrow could be a 1×1 key, but I have not seen one in any plate layout with a 1.25 key its right, but you might want to use a 1.25 key there anyway to minimize cutting. Otherwise, if left-arrow is 1×1 then your Fn key could be a 1.5u key.
You would have to get a custom plate made, or modify an existing one.
I had modified a winkeyless plate to fit a 6u space bar. I used a hacksaw and a set of needle files to enlarge some holes. Some cuts were made with the hacksaw blade facing up instead of down. Do not cut all the way with the saw - use the files for the rest, especially the corners. Be very careful and measure with a ruler and an engineer's set square between each cut. F12 is in the same column as up-arrow.
