With regards to caging, if you can move your snake into a bigger tub than the 36", you may want to consider doing so. Not sure what you have available for totes out in your neck of the woods (I recall you saying it's relatively slim pickins), but keep your eyes out for a bigger enclosure if possible. If you can get your hands on a Christmas tree storage tub, that may ultimately be your best bet, and will give your snake plenty of room so that you're not having to switch enclosures around too often. Ultimately 36" x 16" x 12" is going to be a little snug if your snake is 50", especially when you're working with a RHP to regulate temps.
Bloods & short-tails are all very vocal. They have a large primary lung that is over half their body length, so it is normal to hear a lot of hissy huffing and puffing when you handle them. There's a marked difference between this and an actual PO'd "leave me alone" hiss.
Keep in mind that the more confident and nonchalant you are towards your blood's behavior while handling, the more the snake will calm down with short, frequent handling sessions. Try to always end them on a positive note. These snakes remember negative experiences and also learn pretty quickly that if they throw a fit & you put them away, you'll continue to leave them alone, hence they'll continue to throw fits.
Calm, frequent interaction (just a few minutes a day) is key with these snakes. Develop a routine that allows your snake to anticipate handling on a regular basis, be patient, and you'll see some changes in behavior.
Good luck!
K~