I've got a kit to fit as well.
Looking at other cars, the correct height will put them in the middle of the bumpery bulge.
When I get a round tuit* I will take the skin off the bumper and see what is behind it, rather than cut a hole and find I can't push the sensors in.
I intended to fit the squeaker and controller in the boot, and jumper a reversing lamp for the power.
I got the £15 Maplin kit, then spotted £19 kits on eBay with wireless distance meters and colourcoded sensors, so I might get one of those too.
WhenI get the afore mentioned round tuit, I'm junking the Nissan radio and fitting my Sony, then filling the other half of the hole with a clock that I can see and a small cubby, ideal for the wireless display.
(most kits come with the correct sized hole saw, so they are fairly easy to fit once you work up the courage to wreck £500 worth of bumper. The Maplin kit has stick on sensors as well as permanent ones, so you can test out the placement before you cut any holes)
*A round tuit is a small plate that you used to see at seaside gift shops. When I get one, there are a great many jobs that I will do
Hey there, if you want a pro job at little cost and colour coded to suit yourcar. sensors included in the price come up to me in East Yorkshire just off junction37 M62 and Ill fit them to your car all in £100#Mike