The Jaeger break-open block action is not "complicated to make". The only close fitting needed for function and durability is that of breechblock to barrel face, underlug and top extension. All other fitting is just for show. In fact, the fitting of breechblock to the crosspin holding it to the action body has to be loose to allow proper function. In his patent drawing F.Jaeger indicated an out of round hole here by some dots. As the action body takes no strain on firing it may be built very light, fi of light alloy. No need for strengthening bolsters here.
If I wanted a light, single-shot long range mountain rifle with a break open action, chambered for a high-intensity cartridge, I would opt for a Jaeger-type break-open like the Merkel K-series, the Blaser K95 or one of the Ferlach rifles.
But on a double rifle intended for dangerous game the Jaeger action is impractical IMHO, as any top extension, even a Greener, Westley-Richards or Bissel risig bite one, impedes access to the chambers. This is not a new idea, as OttoMaretsch wrote in his 1910 book "Moderne Jagdwaffen" that the conventional action with double underbolting and Greener crossbolt is often used successfully for heavy double rifles, proved by the British large game rifles.
If you are looking for a really complicated dr action, have a look at the Carl Eyring, Suhl 1910 design. Eyring inserted two boltheads, each with two locking lugs, into the action face. These boltheads are turned 90 degrees by the toplever and lock into recesses in the extended barrels. (pic from Maretsch's book)