I was hugely bugged about the persistence issue when accessing FT on my iPhone until about a year ago. You might give the Puffin browser a try. In the Settings pane there's a Site Preference option that you can set to Always Open Desktop Site. It's not infallible but functions more reliably than FF, Safari or Chrome mobile. One caveat, tho: I don't know whether or how advertising affects the experience for a non-mod (since mods don't see ads).