My yaris,with space saver, had a polystyrene cone to support the boot floor. Full sized spare was slightly too tall. I had to raise the whole floor by about 25 mm (1" in Rees-Mogg speak)
If a full sized spare fits for height, but you cant find a Honda insert tray try looking for something from a more common car.
. I saw one on fleabay a while ago from a Renault clio . Tray, special compact Jack and tools for less than £20 inc postage. From a scrapped car but appeared unused. Less than the cost of a new budget quality universal jack that would have been too long.
Lots of other cars have jacks and trays that will fit within a full sized spare. I just searched at random for a few common small cars and soon found something that would suit the jazz,as long as you are not too precious about originality. i didnt buy one in the end as I found I already had a suitable jack amongs the junk in my garage.