The pics dont really show how the current nudge bar is attached but Im guessing its the same as the nudge bar on my wizard. This has 4 light bolts underneath attached to brackets bolted to the front body mounts. This type of fixing is only really for show.
You havnt included any pics of the hilux bull bar If it is a full bumper replacement ARB type you got it at a very good price. These normally bolt to the same mounts as the current bumper which is the strongest way and very likely the easiest to make fit. This is 2 12mm grade 8.8 bolts on each side. My 94 bighorn was like this when I bought it but the mounts had an extra hole each side for another 12mm bolt into the same place as the nudge bar. As I now have the winch and had the mounts modified to take rated tow hooks I have also bolted through this 3rd hole. My bar isnt coming off and thanks to Howat engineering neither are the tow hooks
I wouldnt be surprised if the hilux mounts directly to the bumper mounts without mods
viewtopic.php?f=29&t=6363&p=40509&hilit=bighorn+is+dead#p40509
Sanding your knuckles before starting work can help. That way you cant skin them