Steel isn't that heavy.
I'm sorry, i'm not going to be able to tell you which brands to buy, but it sounds like you ought to go custom, with your leg length problem and the couplers and all...
We ride an old heavy aluminum Burley (okay, not that old, at least 10 years old)
if you are a control freak, or even someone that likes control really a lot, it could be hard. Do you trust your DH's driving? then you'll trust him on the bike.
What we've learned is that I like to be on the tandem out in the country, but in the city it's much too stressful for me.
We've also learned that the tandem beats HANDS down 2 singles in ANY wind.
It's fun to be able to pat your Dh's butt while you are riding.