Externally clocking ALTLVDS with a large number of channels

In the SIV handbook search on the table "LVDS Channels Supported in Stratix IV GX Device Row I/O Banks". I assume you're in the 1152 package, which supports 56 TX channels. The problem is that half of them are on the left side and half on the right. The PLLs on the left only drive the left channels and same for right side. So you will physically need two PLLs to drive that many channels. Is it one device that really needs 29 or multiple devices(unlikely since it's an odd number). If it is multiple, then you can split them. If one device, maybe you don't need one of the I/O? I had one user not hook up the LSB.