Ended up throwing all of my previous choices out the window and going with something that I knew all along would be extremely practical:
HiSi Jamaican Can Bubbler from High Priority Glass.
First of all, videos of diffusion from the included downstem look great. The angle of the downstem will prevent the HI from getting in my face during a hit. The mouthpiece and downstem are both removable (and 18mm), allowing you to insert the downstem into the vertical joint and the mouthpiece into the 45 degree joint, or vice versa. Plus, this will be comically easy to clean/pack up for travel, etc.
I had my eye on this for a while, but it was out of stock at HPG and not sold anywhere else. Last night I was looking at bubblers and tubes with my wife, trying to finally make a decision on something. The HiSi caught her eye, and it had been screaming at me as the most practical choice in terms of stability, cleaning, versatility and diffusion for the money.
Decided to call HPG to see when it would be back in stock, expecting "sorry, we never know when things are coming in stock." Instead, the clerk tells me they have one in, and to refresh the page in 5 minutes. Lo and behold, the clerk immediately updated the website, allowing me to buy the piece. $160 bucks shipped with 15% off. +REP for HPG.
Gonna be a happy 4/20 motherfuckers, FUCK COMBUSTION.