There are a few things I`d like to mention about that article.
(a) Sheldon specifically stated that even what he was doing was NOT recommended for 1in steering tubes or steering tubes made of carbon fibre. According to what I recall from this post, the OP has a 1in steering tube.
(b) The configuration that Sheldon put together was SIMILAR to what the OP whants to do. but there are CRITICAL diffirences.

For example, Sheldon installed a long sleeve with an integrated clamping system over a tube of continuous diameter. The OP wants to install a steering tube entender which will have a tapered profile in the area that would be clamped using a set-up like Sheldons and in the area that the spacer rings would fall according to how the OP first described his intentions. Neither or those could be considered `safe` because there would be too much chance for play.

And lets not forget the most import element -experience. Sheldon had the experience and background to analyze available components and identify and seperate workable parts combinations from potential problems. The OP is attempting to do something similar and is asking for help before even starting.

So lets be clear. There`s a chance that the OP has a combination of parts that MIGHT make this feasable. That doesn`t change the fact that it`s neither cost effective nor ideal as a solution and any info I`m personally providing I consider similar to addressing an emergency repair with stop-gap solutions using whatever`s on hand.

But this guy certainly won`t be the first to do that nor the first person here with more time than money. Personally if the solution is workable even on a short term basis than I`d be interested in how it turns out.

A few years back at least one manufacturer was using these steering tube extenders 9With threaded headsets) in $1,500 bikes so my only real concern is preloading that bearing system. If it can be preloaded with a threaded locking nut independently of the steering tube extension then IMO safety issues have been addressed.