I found, for me, what you describe in a Rifles Inc 284 with an extended box on. Rem 700 lefty SA. I replaced the bolt with a PTG one. Scoped it comes in at 6.25 lbs. Have taken game to 500 yards. Very accurate. But they can make up a rifle fitting your criteria in any number of cartridges and configurations. However, considerably over the cost of the OTC offerings you mention.
While I have a Christianson Arms Ridgeline in 243 and like the quality, it’s far from a lightweight with its scope. But a friend’s son has one in the other (?) model in 300 PRC and it’s much handier. Again quality seems to be there.
