My GQ has 3" lift on suspension and another 2" on the body.

The concern is if I have a flat tyre either on road or off road, the stock bottle jack won't be able to raise the car high enough to do a wheel change. I know there are high lift jacks available for 4WD's but I would rather not carry all this extra weight.

I was thinking something light like either a block of wood or rubber/non-slip plastic that is just the right size to be placed between the ground and the bottle jack should do the trick. For off road situations, I think it would be even better than a high lift jack as you are spreading the weight across a bigger surface area by using a larger block under the jack. So basically if you're on a dirt road the jack won't sink into the ground.

Biggest problem at the moment is finding something suitable to use as a base for the jack. I went around to several auto shops but to no avail. What do you guys think? Thoughts, comments, alternatives?