Ok, I've searched around some more and understand a lot more about the problems associated with this. I get that the explanations given on WSGF, etc, don't work because they refer to using an outdated patch exe. But there must be some way to play in 1680x1050 without causing incompatibilities, right?
Are you talking about this thread: Widescreen in Patched TSL...? Because that one doesn't seem to offer any solution to the exe issue (as far as I can work out). If there is some other thread about this that does offer a solution then please do link to it.
Alternatively, is there any way I can play the game in 4:3 format? I mean without the game being stretched out over my 16:10 screen? I just can't stand to see the aspect ratio so distorted.