As you note, Clark thinks strategically, so of course he has to reckon with where opposition to him running would come from, exactly how it would react to his entrance into the race, and who would be willing to stand with him if he ran. I think you slightly (only slightly) overstate the direct influence the corporate wing of the Democratic Party now has on his decision. I'm sure he knows that much of it would ultimately agree, reluctantly if need be, to ally with him if his candidacy took root and grew and showed strong signs of leading to victory. I don't think Clark is seeking much encouragement if any from them in advance. But he knows he needs to have an initial flight plan sufficient to get his campaign aloft and into contention, likely in the face of, at first at least, corporate Democrat antipathy.
If Clark can find enough relatively non mainstream corporate aligned and/or progressive support to propel himself firmly into the mix, Clark knows he can start to change "facts on the ground" through changing the dynamics of the race, which would force a sufficient degree of the "opportunist wing" of our Party, as you so nicely describe it, to accommodate themselves to accepting him as our standard bearer. Oh I'm sure Clark is keeping open ties with them now, he's too good a tactician not too, so as to hopefully smooth their transition to openly supporting him later in the process, if he does run. Al Gore, and every other Democrat who is running to win rather than primarily make a statement, I'm sure does the same.
As a career military man who always took the concept of honor and service deeply to heart, Wes Clark constantly chose his personal integrity over personal wealth throughout his long military career. Sometimes we act like that is a shocking thing to find in an American leader, a sad commentary if ever there was one, but many of us are personally guided by those priorities ourselves, and career military service is not a path chosen by those who value personal wealth highly.
Col Hackworth once wrote about an interview he did with Clark that bears on this :
"It took months for Clark to get back in shape. He had the perfect excuse, but he didn’t quit the Army to scale the corporate peaks as so many of our best and brightest did back then. Instead, he took a demoralized company of short-timers at Fort Knox who were suffering from a Vietnam hangover and made them the best on post – a major challenge in 1970 when our Army was teetering on the edge of anarchy. Then he stuck around to become one of the young Turks who forged the Green Machine into the magnificent sword that Norman Schwarzkopf swung so skillfully during Round One of the Gulf War.
I asked Clark why he didn’t turn in his bloody soldier suit for Armani and the big civvy dough that was definitely his for the asking.
His response: “I wanted to serve my country.”
http://www.sftt.us/cgi-bin/csNews/csNews.cgi?database=Hacks+Target.db&command=viewone&op=t&id=35&rnd=908.3537190930426So I find it significant today that Wes Clark managed to get to a point, arguably, where he can be elected President of the United States, without either having spent a life time accumulating wealth as a key to power OR depending on those who do so to have financed his career, in multiple installments, every election cycle for decades. It's significant to me that Clark spent his life time rising to the top of an institution that did not reward the best, brightest, most lucky, and/or best connected with pay package compensation thousands of times higher than the base pay of average workers. Clark's own pay barely topped out over 100,000 a year in the final few years of his 35 year career in the Army.
Which is to say that Clark's personal expression of his own life priorities, and his subsequent life experience of working inside an institution that at least partially embraced a minimalistic base form of socialist economics (all housing, health, and education costs fully covered for those who are an active part of the organization, with meaningful - on paper anyway - retirement benefits for those who served) reinforces his vision of a society that functions best when at least the minimal needs of all of it's members are looked out for.
I accept that Clark is no intrinsic enemy of capitalism, and that he accepts that some manifestation of Corporatism is a given that will not be erased from a 21st Century World, but I think he believes unconstrained greed is a direct threat to Capitalism also, because it threatens the health of the societies that Capitalism needs to function in. In that way Clark I believe is capitalist "friendly" in a manner similar to how Teddy Roosevelt was capitalist "friendly". We can do a hell of a lot worse, and we almost always do.