Zim - For what it's worth - I tried some of the laminate stick-on protectors (Ventureshield iirc) and on smaller lights (car factory fitted fog lights) the heat build up cracked the glass. The glass wont shatter due to the laminate/adhesive - but it's till an MoT fail here. You need about 6-8mm non laminated (unprotected) glass around the edges - metal bowls act as heatsinks and help.
If it were me - I'd cough up and fit the Kiwi stuff - unless you aiming to catch a large nugget or two in the reflectors. The grill idea is an MoT fail here too.