Moving it further away from the EP will increase the dispersion, so that will help to spread the spectrum length ways. Try putting it in the front of a 2" barlow - maybe unscrew the barlow lens and screw it in - provided you can still focus
.
To get the spectrum wider for visual use I think there was another grating (rainbow optics maybe?
) that came with a cylindrical lens to spread the spectrum across the width. But see how you go without first - because spreading the spectrum in width will also make it dimmer.
I don't think I've ever really tried mine for visual.
Al.