ok, so we are dealing with a straight spacer kind of scenario......
now, i am assuming a couple of things here....
1. you don't have 19" rims right now
2. tyres will come down in profile proportionally to rim increase
As the rim widths are the same, then you can simulate the clearance with some 10mm spacers, should you not want to risk buying expensive things to test with.
Grab a cheap set of spacers off fleabay that'll fit, buy the cheapest you can find as you'll only use them for static testing anyway and then see how your current rims look with them fitted do not drive around with them fitted, use them only for static testing, because your wheel bolts will be the wrong lengths
Alternatively you can get something 10mm thick, placed against the rim to simulate the extra extension, and see how it will look.
Tyre width at the side wall should not change much assuming you are using the same width tyres as now, so you are unlikely to lose or gain any noticeable advantage
Things that you need to keep an eye on would be something like the following,
1. extending too far and rubbing on the top of the arch under suspension compression, maybe needing the lips rolling
2. if you extend out too far, when you turn the tyre may rub on the inner arch at the front or back, as extending out causes the wheel to effectively seem wider given the pivot point not moving
3. suspension clearance should not be an issue, you should gain clearance
4. Make sure you get the correct length bolts
5. Depending on the wheel design, ensure you still have clearance to the calliper, this i would not suspect is an issue in your case
6. be aware of trim/bodywork changes, for example on mine the rear bumper has a lip where it joins the body work and that was the section i rubbed very slightly on, slight clearancing of such areas may be needed
ok, that's about all i can add for now, it's not the definitive answer you were looking for (and i'm hoping someone with experience of this model will chip in soon) but it'll give you an idea of some of the things to consider.
Personally, i'd try the spacer idea as a test, it's the least costly method i can think of