You want a Mestos PD-K5HL - An L-plate that will fit the K5 with the grip. It does not block your ports and will fit Arca Swiss style quick release mechanisms . My Mestos matches my Kirk ball head perfectly. I purchased one of these off eBay after seeing references to them here on PF. The seller on eBay I purchased from is "
dhsummer". It's weird, as that seller does not seem to have anything up for sale right now, but I would still try contacting them and ask about the PD-K5HL. Name that specific model, as they also had one that was the K5 L-plate for use without the grip.
The Mestos plates are, as best as I can tell, every bit as good design-wise as, say, Kirk or Really Right Stuff. The only minor complaint I can come up with is the powder coating on the plate might be ever-so-slightly below the bar set by Kirk and RRS. Seriously, we're talking 9.75 out of 10.
Come to think of it, I bought my Mestos almost exactly a year ago. I had originally contacted dhsummer perhaps in December of 2011 and I was told they were out of the plates right now but would possibly have more in March. I wrote again in March and luckily they had manufactured more. Mestos seems to be made in South Korea, and that's where dhsummer shipped from, but the two week wait was definitely worth it! I don't want to sound like a shill, but Mestos really impressed me. To boot, I was happy I didn't feel left behind by Kirk and RRS which make L-plates for every CaNikon under the sun!