How Bad is this Derby Betting Strategy?

[Late Fires]

Say I have $400 that I'm willing to lose on the Derby.

I have four horses that I've selected as the most likely winners (call them #1-#4) and four others that I think have the best chance to hit the board behind those winners (call them #5-#8). Do you think betting the race as follows makes sense:

$1 Exactas:
1/All; All/1
2/All; All/2
3/All; All/3
4/All; All/4

$1 Trifectas:
1/2-8/2-8
2/1,3-8/1,3-8
3/1,2,4-8/1,2,4-8
4/1-3,5-8/1-3,5-8