I did not know disabling that was an option. 
I could have made use of that a few times, even if it only snuck in an extra line or two.
I think the main crux is the title, category and tag block, as you don’t really need that on screen the whole time. I don’t know if there’s any nifty solution to tuck that away somewhere and bring it out only when wanted, but that might increase the available space for more involved OPs on your phone.
I’ve made quite a few bigger topics on my phone, and it can get a little claustrophobic at times. There are some good tips in here so far though, and I’d wished I’d known about some of them sooner.