Update: I've received the Plugable USB 2.0 to Ethernet adapter. Note it has the same AX88772 chipset as the Trendnet adapter I had sent back.

The good news is that my N900 was able to recognize it and connect to the LAN. Also good is that it does not feel as hot as the Trendnet; note the Plugable has a larger plastic case.

Unfortunately, the battery again drains in an hour, even if the N900 is left alone. I am considering several options:

a) when not in use, disconnect the adapter from USB mode. However, this does not solve the problem of being unable to use the LAN for an hour at a time.

b) the chipset has a suspend mode. However, I do not know how to utilize it.

c) get a powered USB hub. Since we are connecting to the wall (RJ45) anyway, there is sure to be a wall socket nearby. Also, this has the additional advantage of powering other USB devices (mouse, keyboard). I'm not sure if it would allow for charging of the N900 as well ("USB host mode with charging" in USB mode). The disadvantage is that it's more cost and bulk.

Also good is that I got it to work so that Maemo applications (such as the web browser, HAM, online accounts) now believe they are connected and no longer try to connect to 3G. I installed a dummy/null network (here is the link again). Note that I installed the null (not dummy) network, because only the lib for the dummy is in the repository. Also, the Dummy Network did not show after installing the lib (and rebooting), so I had to use the gconftool command line. The connection manager now shows a Dummy Network. I can connect to Dummy Network before or after connecting to the LAN (with udchpc), as long as it's before any Maemo applications are run.