I just installed my Basslink this evening and spent some time experimenting with it. The remote bass control is really only necessary if you like to adjust the bass level depending upon the type of music that you are listening to. Personally, I've found that once I find a sub level that I like that I never adjust it again.
There are a variety of ways to control the volume level without the control. I decided to disconnect my back speakers and I used the back speaker outputs as the input to the sub--the result is that I can shut off the input to the Basslink by adjusting the fader all the way to the front. For some reason I didn't get a good input signal using the speaker-level inputs so I used a line-level converter instead.
From what other people had told me, I was expecting to be underwhelmed by the sub. Once it was installed, though, I found it to be fine for my needs. It is a sub that will adequately round-out the bottom end but it doesn't thump--a part of the reason for that is how well sealed the BMW trunks are! My car didn't have a ski passthrough so I bought a chisel and knocked out that piece--it now lets in enough bass to sound good. I tried a variety of locations within the trunk and it didn't seem to affect the volume or quality very much--you can pretty much place it wherever you want in the trunk. I'm going to mount mine so that it fires directly through the ski passthrough.