Don't have any qualms about putting a space-saver on the front; it will be absolutely fine. You might be interested to read the following, which I posted a few weeks ago.
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"My recently-acquired 2010 EX (16" alloys) didn't come with a spare wheel and so, like many others, I decided that I'd like to have one rather than rely on the can of gunk. There's a lot of information on the subject on this forum, some of which I was a bit sceptical about, so I thought I'd share my experiences, in case it helps.
My overriding principle is that I don't give Honda a penny more than I have to, so I bought, on eBay, a 16" space-saver wheel and tyre from a Mk.5 Astra, which arrived this morning. It appears to be in brand new condition and cost £28.05, including carriage. For those who are interested in such details, the tyre size is 115/70 R 16 92M, and the overall diameter is 22.3", compared with 24" for the car's normal wheels.
I found that it fitted onto my car perfectly, using the normal wheel nuts, and I've just finished giving it a thorough test, both on the front and back of the car. I took it up to about 45 mph and I can report that it functioned perfectly, with no handling, steering, braking, vibration or other issues whatsoever, and no illumination of ABS / VSA warning lights. Perhaps a tiny bit more road noise than usual, but that's to be expected.
It fits beautifully into the well in the boot (after removing the polystyrene insert), and is held down very securely using a bolt I found in my garage and a metal jam jar lid with a hole drilled in the centre. (I had to make a small hole in the carpet for the bolt.) Total outlay: sod all. There is plenty of room in and around the spare for jump-leads, warning triangles, gloves, inspection lamps, umbrellas etc.
I reckon I've saved myself at least £170, and have the additional satisfaction of having given the extortionists at Honda not a penny!"
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By the way, I think punctures are much rarer these days (better tires, better roads). I've only had one in the last 10 years. Finally, I love your magnetic sign idea, though I seriously doubt whether it will make the slightest difference to the behaviour of the average bone-headed lorry driver.