It will work inverted but in my opinion side mounting is worth the trouble. This does a couple things that I believe really helps, not only am I convinced they oil better but it gives you a leg up on speed regulation. Side mounting a 4 stroke puts the intake outside the fuel head. Think about that for a minute.. Airplane slows down, centrifugal force on the fuel head decreases and fuel head pressure decreases, engine leans out a bit and speeds back up. Airplane speeds up, fuel head pressure increases, engine richens up a bit and slows back down. It's subtle because muffler pressure is minimizing the effect and also acting as a damper on what is basically a closed loop regulator. Another item that hopfully won't happen, is should something go slightly wrong and the ground/pavement end up 2 foot higher than it should have been. Guess what is going to be the first thing to hit with an inverted engine.
I haven't seen the SV-11 and not sure how the front end is built. If you can cut off the maple mounts and epoxy a 1/8 plywood doubler to the firewall you are almost home free. Try to keep the thrust line in the same location but don't be too worried if you end up needing to lower it a bit. I personally like the two piece SIG mounts (SIGEM001) because they allow the intake to be positioned back against the firewall.
Installation isn't real difficult, first drill one of the mounts for the engine positioned as far back on the mount as you can with the intake just ahead of the rear of the mount so it will clear the firewall. With the engine bolted to the mount, position it in the airplane and mark the firewall for that mount. Install the blind nuts and bolt the mount with engine in the airplane. Now all you need to do is position the 2nd mount and mark the holes. I have had good luck taping the mounts for 4-40 and using cap screws with a star washers over a flat washer to mount the engine. Long drill bits come in handy and you might need to remove part of the maple mount or ?? in the tank compartment to clear the blind nuts. I would probable go in with a Dremel and grind off a large portion of the maple mounts in the tank compartment anyway.
Good luck and good flying.
4 strokes are what electrics are trying to emulate