I would not be afraid to experiment like above if the truck is equipped with a pyro. In all honesty, I am a bit scared just to tow with out one. Now, granted I have a CR (3rd Gen) and they are supposed to run a lot hotter, but the idea is the same.

I would recommend looking at where the pump is now. The closer the pump is moved toward the head then the more advanced the timing is. Usually, on these you can advance the pump until it is very close to touching the head and still be fine on timing. I am not saying you shouldn't use a dial indicator to check / set the timing but if you don't have one then it isn't as critical as a guy would think.

The best way to set / only way to measure the timing is with a dial indicator. But if you can't get one, you can 'experiment' with it and get it. Keep an eye on your pyro!!! If it is getting hotter, faster then you need to back off. Don't run it past 1100F on a hard run up a long hill!!! Please! If your truck runs strong now and you don't have a heat problem, then just watch the pyro after changing the timing to make sure you haven't caused it any problem. Make the beginning mark so you can always put it back where you started.
To me the very final word on where timing should be is fuel mileage. If changes you make are improving your mileage you are going in the right direction. Soon as you lower your mileage, then go back the other way! Peak mileage should be the best place to run your timing at. When doing this, make sure you are aware of everything that affects your mileage so you don't get a false measurement.
I have a shop manual for a '96. If you need any info out of it just let me know. It shouldn't be too hard at all to shoot some your way.