then you could try fennec from f-droid, which enables custom extensions and about:config, but unlike iceraven is compiled from firefox stable release, so it is updated shortly after a new firefox stable release.
I take a mental note to try it but I like nightly, I also use it on my desktop and I prefer it to normal Firefox. I doesn't exactly know why but there is something about the regular release that rubs me the wrong way.
Fennec F-Droid does have the same extension whitelist by default, but it also supports the Collections workaround that adds access to all add-ons on addons.mozilla.org:
Since Firefox Nightly is unstable, some users prefer to use Firefox forks like Fennec F-Droid and Mull that are based on the stable release channel, yet also offer expanded add-on support.
Regrettably collections that try to enable everything are cut off at 25 or 50 in Firefox, so it's still not a practical way to recover your disabled addons unless you register with a custom collection.
Unless someone out there made an anonymous collection autogenerator. That'd be nice.