Very cool - a fix that costs 26p - we like those!
Now buy a green (if it's going through a filter, it'll work much better with an LED of the same colour rather than white) T5 LED and get a warning light it's difficult to overlook because it illuminates everything around you like The Green Lantern...
Description for these say they're 5W LEDs, but I somehow doubt that... They probably mean it's equivalent to a 5W incandescent's brightness - but as almost no-one ever quotes lumens (and the figures are often suspect if/when they do), it's all guesswork...
https://www.ebay.co.uk/itm/T10-Car-L...0AAOSwqeVdXpe-
Those have a projector base, so focus light out through the lens - which will probably work better in this application than the ones with just an SMD chip slapped on top.