"Grilling" is not barbecuing (except in Oz).

Boning Porterhouse steaks seems a terribly destructive method of turning a fine cut of beef into something potentially far less enjoyable. Cut thick enough to grill well, 2" or so, a Porterhouse is simply too big for most appetites, and at the high prices likely to be charged, hasa poor cost ratio of consumable end product, lots of bone, fat and "tail"

A couple of "boneless" alternatives which preserve moisture and flavor....Grilling a boneless tenderloin or even a well trimmed boneless rib roast ("Ribeye"). Grilling a boneless rib takes care and attention with controlled heat and requires time. "Butterflying" is tricky, since the "ribeye"'s center is a single muscle and splitting it impairs moisture retention. A "sirloin" roast, cut from the large side of what makes up "Porterhouse' steaks or a section from which NY/KC strip steaks aer cut, is hard to grill because the fat layer on the top side is thick and renders a lot of quick to ignite drippings.

Places like Sam's and Costco sell "Cry-o-Vac" tenderloin strips of decent for about $10 a pound, and they are greatly favored by caterers (who price shop fancy cuts from all sorts of purveyors). The problem with tenderloins? With no bone, little exterior fat and lightly fibered muscle, they will dry out, if left long on over the fire. That's why filets are less often grilled, more often "pan broiled' with substantial lathering/basting to prevent drying.

One "secret" calls for letting the beef stand for a few minutes after removal from the grill.