Not in a 3880. If you were to run P2/K6 and only print on matte (so no GO), then you need 6 channels for K6 neutral, and four more channels for Shades 2,3,4,5 Spec Edition (Shades 1 & 6 are the same), and you have ten channels in a 4900 as I understand it, so I guess it's possible. Given that there's a switchable black, you could probably run gloss as well, provided that you had another printer for the GO coat. Of course the P2/K6 Spec Edit curves would all have to be remapped.
Piezography Pro is rumoured to be being released soon, and my understanding is that it will enable two inksets.
I find that leaving an extra 40mm at either end works well enough. On printers with a roll paper option, the Epson drive will leave this much or more at the beginning anyway, so compared to that, you're only losing an extra 40mm at the end. When I do this I don't have problems with head strikes. There is however a skill in not putting small kinks in the paper from all the handling, and for some reason, these always end up in the sky areas. Certain forms of mounting will help deal with these.
One thing to avoid is printing with a RIP like Colorburst Overdrive (for colour work, not Piezo), as it wants to print the white of the leading and trailing edge, which pretty much guarantees head strikes from the paper curl. QTR, Mirage, Printfab and I assume ImagePrint are ok.