Thank you, Alexander!
I already found the same solution, you suggested in similar post from another user. Sorry, I was going to update this post saying that I found a solution, but I switched to another task and forgot... Never the less, this approach works for me and now I can use Textastic on both iPad and iPhone and it covers my needs for 100%.
RST is also important for my work and it would be great to have it supported in iOS version of the app
Customer support service by UserEcho