Hello Workshoppers,
I'm looking to make a sideboard for the living room that is 450mm deep and want to join the tops and sides with a mitre join like below:

The problem is I don't have a table saw or mitre saw to make the cut and I don't think a circular saw could make a clean cut at that length. The rip tool is only good if I'm working near the edge of the timber, which unfortunately I won't be.
Does anyone know any hacks/tricks to get the same cut with a circular saw? Or will I need to fork out for a table saw?
I've heard of people clamping a guide on top of the sheet and using this but haven't got any feedback on its success (or failure).
Cheers,
Luke