Looking for tips / advice on an addition to doublewide

Greetings all. I own a 2496 sq foot mobile home (double) on 3 acres. I'm considering an addition soon. We have 5 kids, and my wife and I are wanting more space for ourselves / home office / private kitchen.

Some options I've considered.

  1. Adding a second mobile home (to make an L shape) - this would give us an extra bedroom, an office space, and our own kitchen.

  2. Building a second story - this would give us a lot of extra space

  3. New construction - building on an addition. This may end up costing more because it's an entirely new addition.

For those who have done this sort of thing, what did you do? What did it end up costing you?

Thanks for any tips!