> Couldn't you force trucks onto Furman street

Potentially, but the turn at Old Fulton may be problematic for trucks, it would need to be studied. Any truck diversion route would of course get pushback from local communities as well, complicating the problem. Trucks going northbound on Furman can't re-enter the BQE until Sands Street, which again could be problematic but may be the best option.

> So build a new temporary trucks only road through the park.

Definitely not possible, Parks dept would absolutely not allow destruction of park property for such a use case, nor is park land suitable for trucks. It may also be impossible given the terrain and geography of the park, as well as multiple buildings in the way. I think 'environmental disaster' would be the headlines used for such a proposal lol. Much of the park includes piers and water front activities that should remain accessible regardless of construction, so it's not as if the park will be vacated.