I have a 7'2 heavy worm and jig rod in the shimano clarus lineup. The lure rating is for 1/2-1 1/2. My question is that I was wondering if I could get away with 3/8 or a little less considering it is a soft heavy

Do you mean you are using a 3/8 weight plus plastics, you might be able too.  Try it out, worst thing that could happen is that you make get a backlash.

I have basically the same rod but in the Crucial line. I throw 3" tubes with a 1/4 oz internal tube weight all the time with no issues. It will launch them

I have basically the same rod but in the Crucial line. I throw 3" tubes with a 1/4 oz internal tube weight all the time with no issues. It will launch them

Well Clarus vs Crucial is a pretty major gap imo...I find that my Compre compared to my Crucial is not the "same".  Saying that however, I'm sure he will be able too.  Just not sure it will be the same as your Crucial regarding the tip being soft enough to load. 

As far as the tips of both rods, I have either used or messed with both in almost all the powers. They were extremely close if not spot on. There are some major to minor differences in them, but for overall casting of light baits, they are almost exact.

I have that jig rod and threw 1/4 ounce jigs on it with ease. I use a lews tournament speed spool reel on it and I love it.