I know most view this as completely unsafe and for most people it probably is.
You're an adult. Make your own choices. I believe we'd like for them to be informed choices, though, and your dive description puts that in some doubt. Please do not be offended when I say that upon 1st reading your post awhile ago, I figured it was likely a joke, a caricature deliberately hitting on a range of things newbies shouldn't do in such an over the top way as to be obvious, and that I'd look guilable if I responded seriously.
Since evidently you were serious, I say that to offer some insight, not to insult you.
For a new OW diver, on his 1st post-cert. dive...
1.) Diving well over 60 feet is really a bad idea. Diving well over 100 feet, which is the bottom limit for training in the AOW course, is even worse. Doing so without good buddy procedure and not knowing how you will respond to getting narc.d is even worse still.
2.) Task loading is one of the big problem issues in diving to begin with. For a new diver, buoyancy, keeping on top of depth & PSI readouts and watching NDL readouts, keeping up with a buddy and observing the environment in a 3-D world (stuff can be above & below you, unlike on land) with reduced peripheral vision (mask + underwater zoom factor) & the loss of directional hearing and the ability to speak, in an alien environment dependent on gear that can fail, and breathing off even a good reg. is still not comparable to the respiration we engage in at the surface. Being a newbie, you got caught up trying to get your gear set up, so your familiarity with it was limited (no shame there; it took me quite awhile to catch up to snuff on mine). In addition to all that, you took a potentially dangerous weapon (a spear gun) down to engage in an activity that lends itself to focused attention (spear hunting) at depths putting you at risk of diminished mental ability due to narcosis, without adequate buddy supervision. And while the pony is a good idea, it also adds to gear complexity.
3.) Did you indicate this was in 15 foot viz.?
If I were going to devise a caricature dive for a 1st post-OW dive, I would almost surely not have come up with all that, and I'd be hard put to improve on it.
Oldenred, you're an adult, and you decide what you do. But please, for the sake of yourself and all the people who love you, get more training and experience before you do these kind of dives. I've got over 200 dives, and I'd have to think long and hard before I tried the dive you just did.
Richard.