I don't think you could install a Harris bi-pod on an SP-1, because the split in the handgaurds is on the top and bottom, not on the sides. The holes are larger, too. The plastic around the holes is thin, and probably brittle. You would be trying to pull the mount tight against the heat sheilds and the plastic furniture.
If you got to the range, the handgaurds would likely flex and the bi-pod would break the plastic and fall off. More likely to happen would be that you would ruin the handgaurds trying to do the initial install.
You would need to attach the bi-pod to either the bayonet lug (anyone make one like that?) or the barrel just in front of the handgaurds. Don't know if anyone makes one for that style attachment, either.
I'd suggest the G.I. clamp-on as the best solution, but I scratched two barrels trying different ways to pad the sharp edges on the damn thing. It has very sharp edges where it grabs the barrel, and it will eventually eat through just about anything.