Alternate Gameplay: Range in which Dynamite Explodes can be Extended

A house rule for dynamite might be to allow the range by which dynamite explodes on a "draw!" to be extended. When dynamite is in play, each person on their turn is allowed to discard 1 spade to extend the range from 2-9 of spades, to a 2-10, 2-J, etc. The idea is that the fuse is burning, and the chance that it will explode will increase. Spades can continue to be discarded until the range reaches 2-A (approx. 25% chance of explosion). The extended range is permanent until a dynamite explodes. Each discard could up the range by 1 or 2, depending on how useful you thought this option could be. Obviously, you would want to up the range to up the chances of the dynamite exploding before you get to your next turn.