With a grip you CAN use the RB67 handheld, but not so much carry it very far. My RZ is lighter and I sure wouldn't want to carry it much, but I have used it handheld - briefly.
I was going to say to just hire a porter to carry it and get an RB67, or maybe a GX680.
Or just get a Speed or Crown graphic with a rollfilm back. They were actually designed to be used handheld, in the days when people were more up to challenges

and give you the option of 4x5 sheet film, and for that matter different negative sizes in the rollfilm backs. Of course there are always the "baby" MF versions. Not really a "carry anywhere" but I guess you can carry a refrigerator if you're strong enough and determined enough.
Of course I'm being silly but the thread left the silly station some time back.
I am fond of TLRs, but I don't have a problem with the reversed view in a WLF and I don't usually get along well with rangefinders. Much of this is a matter of taste, including how big and heavy a camera one is willing to "carry around all the time."