R350 rail solution for short depth rack

I'm awaiting delivery of a couple of PowerEdge R350 servers, to be installed in a relatively short-depth rack (560mm).

I'd like to mount the units on sliding rails, but the standard Ready Rails for the R350 require a minimum 608mm or 631mm rack depth. (https://i.dell.com/sites/csdocuments/Business_solutions_engineering-Docs_Documents/en/rail-rack-matrix.pdf)

Does anyone know of a good sliding rail solution for shorter depth racks?  I'd prefer not to just use chassis support L-brackets.