Yeah we want videos! Not just flight but let's see some of that removable nose action too. I've had making a 3D printed body for my 75% Goblin on my someday list and I'd love to see what you've got there. I really like the way the vertical stabilizers are enclosed by the fuselage at the bottom, that's a real nice touch that probably eliminates all the flex in them.
As far as small ESCs with BECs, I'd say the easiest thing to do is just stick a 5V buck board or LM7805 to a regular ESC and then just replace the 2 wire (GND/SIGNAL) connector with the standard 3 wire going back to the receiver with 5V injected on it. If you search eBay for "mini 5V buck" they have these tiny 20mm x 10mm switching step down regulators ("UBEC" as they like to call them in the RC world) that are perfect for mating with a modern tiny ESC and only cost about $1-$2 each. LM7805 / 78M05 are the BEC regulators you usually see built into ESCs and are like 10x for $2 although they get much hotter the more power you pull and the higher the battery voltage is.
EDIT: Amazon
has something similar 5x for $11, with the real key point being they have the solder jumper on the back to set a fixed output so you don't ever worry about brushing against the adjustment potentiometer and changing the output voltage.