Hi,
Proofing on an inkjet printer will, at best, only approximate the print on a commercial press. If your files are to be printed in cmyk, you are best to do a soft-proof in Photoshop using one of the standard cmyk profiles. You cannot do cmyk soft-proofing in Lightroom or, as far as I know, any other image processor.
The Epson large format “Commercial Edition” — not Standard Edition — versions printers combined with a spectrographer are a proofing solution, but that may not be necessary if the print quality is to be “pleasant colours” as opposed to “accurate colours”. In my experience, proofing in Photoshop was quite sufficient. For more precise proofing I relied on the pre-press proof from the printer, or less frequently, when accuracy is paramount and budgets available, on actual press proof.
If I were you, I would start with the on screen proofing in PS.
Jean-Michel