Instead of a rear sight, how about a picatinny rail? I'm sure it can be done!

I like the Samson rail option, by why not just a rail?

All kinds of companies make parts for AK's, but I haven't (yet) seen a company make a built in rail. Only add ons.....

That's what the Poles do on some of their Beryls.

Several places are selling AK receiver covers with a picatinny rail made on , I don't think that even means removing the rear AK sight as the scope will "look over" or view above the original rear sight. I don't recall just who had them but get online and give MidwayUSA & Cheaperthandirt a look see....

There would be a lot of labor involved in making something with a built in rail.  Figure to install a custom rear sight block with a built in rail would require pressing off the front sight and gas block.  Remove the factory rear sight block, press the new one in place and pin it.  Then reinstall everything.  Thats a good bit of labor, probably wouldn't be cheap to pay for that install and the rear sight base would probably cost at least $100.  Just isn't cost effective considering most people want AKs because they are inexpensive.

Something like this, except built in from the start?
Scout Scope rail

Tickbite Supply makes the other version you are talking about; a "supplemental" cover/rail which attaches to the receiver to trunnion and goes over/in addition to the rcvr cover.

I've seen the different types of covers and rear sight options. Why not just forgo the rear sight and have a rail instead? I'm sure a backup could be made to hang over the rear cover.

1st post and all.

Millet used to make one, it was a POS.

ACE LTD made one that had an integrated rear sight, but they stopped making them.