I need to rip about 10 1x4 (10 ft long) to 1x3. I have a mitre saw and
circular saw/skil saw but no table saw. I don't have the space or much
future anticipated use for table saw so did not want to invest in one.

I was planning to clamp on one of the 1x4s as a guide and use my
circular saw to do the ripping. Will this work and end product be
acceptable to use as trim on outside of a playhouse? Or is the cut
going to be so crooked as to look ugly?

Any other suggestions on how I can accomplish this job with tools at
hand?

Thanks

AK