Worth digging out 5' crawl space?

I have a modular home, already on a cinder block foundation with a 5' crawl space.

The house is 65' long 14' wide with a 40' x 10' addition on the side.

The previous owner only saw fit to excavate half of the dirt under the house.

There is still a 10' x 40' x 2.5' swath of dirt under the house that will be needed to be removed before the floor could be poured.

I'd like to move my laundry down stairs also use this area for cold and dry storage. Rather then putting a laundry room addition on the house.

What would this cost to accomplish? I can do alot of the work like digging it out but what would be the best way to tackle it.

I'm wondering if this would be a good plan to add value to my property.

Thanks.