cha ching !!!!! my 2c for what it's worth ......

a set of 6" splits in the kick panels and make up some new kick panels to angle the speakers out of the foot well area a little, then mount the tweeter up on the dash. in the doors i'd look at a pair of 6x9"s, probably only a 2way, or if you can find them a split set, so you effectively have a 6x9" sub with an independent tweeter. for an amp a 4channel as a minimum, you should be able to fit this under the seat, or ideally one with sub control to run the 6x9"s more like a sub, and then not connect in the tweeters to them if you get them as a split type.
i think this would give a good sound stage in such a small cabin ... the 6x9"s would give a reasonable bass, the 6" good clear mid and the tweeters the top end.
you'd also want to get some adhesive backed sound deadening sheets to stick inside the doors, on the door skin, behind the speaker. guaranteed you'll find all sorts of new rattles
and as stated before ... you get what you pay for