Ich habe noch einen Link beigefügt, wo man das Teil sieht.

Dies waere mein Vorschlag wenn es sich um einen optischen Effekt handelt indem man eine Verblendung/Verschalung auf etwas aufsetzt um eine verbessertes Aussehen zu erreichen.

This is what I used recently in a press release for VW. The exact word translated there was 'Endschalldämpferblende', which I think means the same as your 'Sichtschutzblende' in this case.
In any event the customer seemed quite satisfied with the translation.

Deutsch term (edited): Seitliche Sichtschutzblende (optische Verlängerung )

In the UK, the general term for this sort of decorative part (Auspuffendblende) is "exhaust/tail pipe TRIM" (rather than tip, cover or extension).

("Trim" implies visually hiding something.)

The term in question here, however, is referring to (borrowing medical terminology) the anterodistal elongation of the part so that the existing exhaust pipe onto which it is being welded cannot be seen from the side through the bumper cut-out.

In this case I'd reword and use a descriptive phrase that, in combination with the picture, gets the idea across without sounding overly "technical" (as this appears to be a marketing description).

Exhaust pipe extension or muffler tip. No literal translation of Sichtschutzblende needed, imo.