You can do quite a bit with a 7x if you sight it to where your impact point is where the top of the horizontal crosshair is at teh feet ground of the PD (but the bullet will hit dead cenyter on the dog) and the vert crosshair is lined up on hte left edge of the dog.
This way you can see te whole dog and it will extend your distance given the cartridge you are suing and the conditions.
A Burris 3-12 LER w/BP would be beneficial or a higher powered rifle scope if you are comfortable using a rifle scope on a SP.
There will be a number of VHM subscribers there, so hopefully we can add a # of SP shooters to the 500, 1000 and even 1500 yard clubs!