In Arizona it is a must to use a sunscreen year around. I have found that the circular collapsable ones that are made a one pieces with somewhat squared corners work best for me. You need large ones that you can tuck the top between the upraised visor and the ceiling. I needs to be large enough that it will bow slightly when at the bottom of the windshield. That will allow the end next to the door to be pushed towards the side glass and not actually touch the A pillar. Insert the passenger side first and tuck the middle under the rearview mirror. This will allow complete coverage of the front windshield and not leave any marks on anything. Easy to remove, collapse and store.
Works for me.
2004 LS430 UL - silver, chrome grille, Auto Couture trunk spoiler, OEM mud guards, 7-spoke OEM chrome wheels. VaisTech SL2Vi
1992 SC400 - Original owner
They make custom fit ones for the LS430, and the dealer can order them. My dealer wanted $36 for one, which seems pretty close the internet pricing. Look at the fit in the link below...the ones you buy in standard, jumbo or super jumbo are not a good fit. I bough one and it has to be folded at the edges to fit, and then it's all bunched up.
The custom fit shield above is a great option. I would also use new 100% (clear) tint on the entire windscreen. This will protect the car when in-motion. It looks like you already have the side and rear windows tinted, but you may want to check and see if you have ceramic. You could opt for ceramic for maximum heat rejection.