My sister and I considering doing a century around Lake Tahoe for a team in training event. She lives in Dallas, TX and myself in Portland. We are at different fitness levels, so we are considering renting a good road tandem for the event rather than separate bikes and not seeing each. We'll bring our saddles and pedals. Is this pure folly? I have captained a tandem a bit and am generally experienced, but I'm looking for some expert opinion - is this a catastrophe waiting to happen? The issues I see:
- lack of prep time together
- different position on bike = more likely to cause pain on longer ride, possible knee issues
- course will have hills (and downhills) - no practice with braking

Thoughts?

Thanks.