As usual on this forum people see an idea (in this case mine and probably others to) and shoot it down without even thinking about any possible benefits. How about instead of just being negative some people actually look at its merits. Having purely negative reactions to people's ideas intimidates new forums members and makes them probably not want to post their ideas, some of which might be very interesting.
There is no doubting that an inverted engine would take up less space. With regards to packaging, I actually think for a team like McLaren with that canted radiators, the radiators may be able to move inwards a bit because less space is taken up further up making the sidepods smaller.
Food for thought.