Are you sure? I can think of one other guy he’s coaching that pulls conventional, Christophe Rebreyend, he is 6’7" and a SHW. I would be surprised if everyone he coaches pulls sumo, but it is possible. I read on his forum that he prefers sumo for most people because a lot of people can’t set up for conventional without rounding their backs. In any case, it looks like most Russian lifters pull sumo.
With regards to training the opposite stance, I remember reading on his site that it says to do good mornings (which are a staple exercise for Sheiko) with the opposite stance of your deadlift. In other words, if you pull sumo then close stance GMs, wide stance if you pull conventional. It’s not exactly a deadlift but he still gets people to train hip extension in different stances.
With the level Belkin is at he probably had coaches coming up through the system but these days if you don’t hear a peep about his coach there’s probably no one coaching him or at least nothing major maybe a nutrition or soviet sport supplement support guy/s or something.
If there was a coach he’d be taking all kinds of credit for Belkin’s success to sell himself but haven’t heard anything of the sort. Or maybe he is being kept a secret by the KGB… I mean the FSB.
Of course there are exceptions. But 95% of his clientele are lifters with low body height. I think Rebreyend had a health problem with hips, so he could not use the sumo deadlift.
That’s very unspecific to deadlifting near 1rm. You could do it as an accessory during a GPP phase of your programming, but as you get near to your high intensity lifts it’s useless and only costs recovery for little benefit.
Wouldn’t more conventional lifting be optimal as an accessory to your sumo in this circumstance? It has high specificity and has the heaviest loading, or you can be more specific to your issue and do rack pulls conventional. That will put the most stress on your back with a bigger lever to act against, I don’t see a better solution if your erectors are weak.
For deadlifts, the better you get at pulling stuff in every possible direction, the better your deadlift gets. I personally like heavy unilateral carries, suitcase deadlifts, heavy sled drags, and zercher carries. I just add them in at the end of a workout or on an extra day.