Quarter and Sheet Panels Installation Advice

I've been replacing sheet panels on a dart and will soon prepare to replace the quarter panels.

I was thinking on installing the truck floor first with trunk extensions,

keep the quarters on to replace the rear deck panel top line it up,

track and weld the rear tail light panel in place to the trunk floor and check trunk measurements,

and then locate the quarter panels temporally to locate the wheel wells and trunk extensions.

When I install the quarters, I was going to place the motor in the engine compartment and try to load up the suspension before permanently welding the full AMD quarters. Use the "All Metal" in place of the lead.

Maybe even place some weight on the trunk floor to simulate the weight of the bumpers.

Does this sound like a good plan or is it over kill? I would think the body will move once the full weight of the car is loaded on the suspension.

Any input would be greatly appreciated. Thank you.