Several ways. One, you can detach the trailer from your vehicle and raise the tongue of the trailer high enough to reduce the angle between the ramp and trailer floor. Or put some blocks under the ramp to raise it enough to reduce the angle of the ramp/floor.
The easiest would probably be putting the blocks under the ramp raising it several inches. If you need to raise the ramp enough that you have problems with the spyder bottoming out getting on the ramp, you can build a small ramp to the ramp.
When putting in my ex's bike, it is pretty low slung, I have to use blocks to reduce the angle. I only need to raise the ramp about 2" for it to work (have the gouge to prove it didn't work the first time
).
Mark