Longview Towing Mirrors # LVT-2300-C are custom-designed to fit on Ford pickups, but for your 1999 Lexus LX 470 we can offer you better options in universal-fit towing mirrors.
K-Source offers their clip-on towing mirror # KS3891 (sold individually) that fits on both driver- and passenger-side mirrors. The linked video shows this 7-3/4- tall x 5-1/8-inch wide mirror that is secured to your OEM mirrors with its ratcheting straps.
If you prefer the widest possible field of view I suggest... view full answer...
My contact at Timbren confirmed this kit includes wide spindles designed specifically for use with wider off-road tires so this should be a fine choice for your application.
The Timbren 3500-lb Axle-Less Trailer Suspension # ASR35HDS01 is indeed fairly new to our site, having been added in October 2013. This kit offers bolt-on (no welding) installation and fits any width trailer frame. It can even be installed on aluminum trailer frames. This product has wide, straight EZ-Lube spindles... view full answer...