(Finally) Migrating from log4j 1.x

All,

My understanding is that under many circumstances, migrating from log4j 
1.x -> 2.x is nearly as easy as simply upgrading the JAR file (and using 
the migration bridge library), but there are some other restrictions as 
noted here:

https://logging.apache.org/log4j/2.x/manual/migration.html

In various programs and services, we are using log4j 1.x in a way that 
might be a little hacky. Specifically, we have a set of classes which 
allow appenders and loggers to be reconfigured at runtime using calls 
such as Appender(Skeleton).setThreshold. Is there a way to do this kind 
of thing in log4j 2.x?

We are also doing things like starting up with a hard-coded 
configuration to print-to-console and then, after loading a 
configuration from elsewhere (which may fail, hence logging to the 
console), re-initialing the logging system, with the new setup (e.g. log 
to file, network, etc.).

The migration guide seems to say "you can't do this", but I think there 
reality may be "you can't do it anymore.... in the same way".

Can I get some practical tips for upgrading from log4j 1.x -> 2.x given 
the desire to do some of the things listed above?

Thanks,
-chris