Flats needed for new layout:

needed	type		in shop		build		borrow
2       1x3				2
2       1x8						2
1       2x12		1
3       2x8		1		2
2       3x12		2
2       3x3				2
1       3x8		1
1       4x10		1
5       4x12		5
2       4x5		2
2       4x7		2
6       4x8		4				2
2       4x8d		2
8       5x10		8
2       5x12				2
Total: 41

To be built:
2	1x3		a bit of luan, trivial strapping
2	2x8		64' strapping, 3 yards muslin
2	3x3		24' strapping, 1 yard muslin
2	5x12		74' strapping, 8 yards muslin

Total materials:	152' strapping ($32)
			12 yards muslin ($78)
		Total $110

If you want to extend the sidewalls downstage 3', you need one more
3x12 flat.  It will cost 32' strapping ($7.50) + 3 yd muslin ($19.50) = $27

What if we make the 5x12s by extending existing 5x10s with 2x5 flats?  We
save 46' of strapping and 6 yards of muslin, for $49.

If we do both, the net cost is $88.

Platforms & steps:
4	4x8		2				2
1	4x4		1
2	1x4		2
2	2'x14" steps	2 (build up to 16"?)
4	backstage steps	(use anything)