battery isolator recommendation?

Can anyone who has experience with a nice-looking, high-performing battery isolator with trickle-charge feature suggest one for me to consider? I need one, I would love it if i could find one in chrome. Of course, I am most concerned with performance and reliability. I am running a deep-cycle battery in the rear for my stereo.

Ultimately, although this may be impractical, I would like to develop a relay that only activates the isolator (and connects the two batteries) when the engine reaches +/-2000 rpm, so that the alternator is not overly taxed at any time. However, the trickle-charge feature may be enough to lighten the load, I am not sure. Anyone have experience with dual batteries w/ isolator? My car is a B5 passat wagon.