Well, it turns out, harder than we thought. The boat was really easy compared to the van. For starters, the boat was free, so we didn't have to worry about ruining something expensive. Secondly, we decided early on not to reconfigure the boat layout, so that minimized a lot of major decisions. And thirdly, the division of labor on the boat was clear--Howard dealt with the completely defunct engine and related mechanical systems, while I took on restoring the wood, paint, canvas and upholstery.
The van, now called Buster, has a less clear division of labor, so we have taken to squabbling about the details--the windows, the flooring, the cooker, the details of darn near everything. Adding to the tension, Howard is a man of action, and I am a woman of equivocation, so although we eventually end up on the same page, we have to travel through the valley of much contention first.
If you are undertaking a conversion project with a partner, I think it helps to clarify your goals right at the start, state your non-negotiable needs, and clearly define your budget. With those parameters in place, go forth and create...and keep reminding each other that this is supposed to be FUN.