Welcome, David.  Very interesting point of view. 

With no intended disrespect whatsoever, I'm going to tell you that I just don't think this experience is for you.  With your background, I would honestly fear for your safety and sanity with spice.  If you think that cannabis can be overwhelming, that it's "too much too quickly", let me tell you... DMT is a billion times more so... a trillion, bazillion times more so.  You cannot fathom how powerful this experience actually is.  It is weirdness beyond your wildest imaginings - and for as long as it lasts, it's FOREVER. 

It sounds as though you know yourself and you don't like being overwhelmed.  This experience WILL overwhelm you in ways that may fuck you up, I'm telling you.  I would think it through VERY carefully before stepping through this door.