There are a few sprite and object clipping indexes that aren't used by any of the original sprites or are exactly the same as other indexes. Sprite clipping indexes 0B and 15 are unused and index 32 is identical to 31, while object clipping 04 is used only by unused sprite 12, 06 is unused, and 0D is identical to 09. These are some hex edits that allow you to use one or more of those indexes for custom values. Sprite clippings are in order of X offset, Y offset, width, and height, while object clippings are four X coordinates followed by four Y coordinates for the right, left, bottom, and top points respectively. The values here are the normal ones.
Code; sprite clipping 0B
org $03B577
db $06
org $03B5EF
db $06
org $03B5B3
db $03
org $03B62B
db $03
; sprite clipping 15
org $03B581
db $00
org $03B5EF
db $FE
org $03B5B3
db $0F
org $03B635
db $0E
; sprite clipping 32
org $03B59E
db $00
org $03B616
db $FE
org $03B5DA
db $30
org $03B652
db $12
; object clipping 04
org $0190CA
db $10,$00,$08,$08
org $019107
db $12,$12,$20,$02
; object clipping 06
org $0190D2
db $07,$00,$04,$04
org $01910F
db $04,$04,$08,$00
; object clipping 0D
org $0190EE
db $10,$00,$08,$08
org $01912B
db $08,$08,$10,$00
; make sprite C0 use sprite clipping 31 instead of 32
org $07F3F5
db $32
; make sprite B1 use object clipping 09 instead of 0D
org $07F31D
db $0D
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