Greased Lightning is perfectly safe to use on car and caravan windows, provided you use microfibre cloths to apply and buff off. Don't use old rags, or scrim cloth, get the right cloths.
However, I wouldn't use it on a windscreen because of the wax film.
I find that you can easily get through half a dozen microfibre cloths when cleaning a caravan. Use one to wipe the GL and muck off, and a second to buff. When the first cloth is really mucky finish with it, use the buffing cloth to do the muck wiping, and introduce another cloth for the buffing. The cloths can be cleaned in a washing machine (no fabric conditioner) on a 40 degree cycle.
I got two packs of large microfibre cloths from Warners
Got a bottle of the Aldi stuff this morning £4.99 just been to give it a try on a section of side panel and also GRP (not ABS/plastic) front and rear panels so easy to use and a great shine, will stock up with more tomorrow