Remote starts do exist for manual transmissions. Unfortunately I cant provide a link right now, but how they usually work is that before you exit the car you have to put the car in neutral and leave the engine running, then press some button on the remote. This enables the remote start. You pull out the key, get out of the car (the engine keeps running), close the door, lock it and press button on remote again. At this point the engine switches off and you are able to start the car using the remote when you return.
If you do not follow this procedure when exiting the car the remote start will not work. It seems like a lot of trouble, but its to ensure the car is in neutral when you start it.
Google "remote start manual transmission" and look through the results. There are many different options.