It seems a lot of work for the 5 users who insist on using old Amiga Browsers for anything other than novelty value!
It really isn't, though. Back before my A4000D took a nosedive, I used to run it's iBrowse and AWeb through my local Privoxy proxy that ran on my gateway NAT/ICS server. Just by that stripping useless junk code out of the HTML, it accidentally improved compatibility quite a bit for the Amiga.
I never thought of trying to present an Amiga browser as an old cell phone. That's an interesting idea. What you'd have to do, though, is find some still somewhat supported phone/browser combo that has such a limited feature set as an old Amiga browser, though. Not the most common thing in the world.