I see. Model diesels work best with adjustable compression and normal carb throttles. Our engines are not injected so you can't adjust the fueling amount for throttling. Injected diesels are really stratified charge engines while carbureted engines have homogeneous air-fuel mixtures. To make the homogeneous mixture ignite it has to be within the combustible air-fuel ratio, if you go too lean the fire goes out. Startified charge is not like this, so reducing fueling works as a throttle.

An ignition system doesn't weigh much, nor does a carb. I don't see where the weight saving would be. Use an electronic ignition in place of the coil type. I'm currently flying a spark ignition in a .40 size on an FS-52. I think glow plugs would be possible using a slip ring arrangement. I don't know how bearings on the crank would handle that much current though.