Good luck!
Just out of curiosity I looked up the Miracle-Gro Tomato fertilizer, it's 18-18-21. Like you Cameron, my understanding is a high P number is good for bananas. I looked up Sul-Po-Mag fertilizer as well because I haven't heard of it. Looks like a good product. Now to try and find it locally. I have to admit I usually apply 2 to 3 times the recommended dose of fertilizer for bananas.