With the Mini likely being centered over the rear axles, i would also recommmend keeping the tandems. The good news of course is that the cost won't increase (except for aluminum wheels perhaps) and that you could always put a heavier car in at some future point.
I don't know your schedule for wanting a coach/Garage but I would be happy to answer any other questions or offer advice. You can contact me throught the forum or our website.
Tony
ToolSet Motorhomes