could a jazz bass with a harder/heavier wood body get a rickenbacker sound?

Nope. A J pickup ain't a Rick pickup.

 

Why not just go this route?

 

Yeah.. just put rick pickups on anything , it will sound like a ric 99.87567%.

 

Honestly with the right set up and gear you'll sound like a ric. Naturally they are similar yet different sounding but I'd really have you listen to the Moving Pictures album from Rush if you're not familiar already. They used a Ric 4001 and a Jazz to record it. You can tell some subtle difference in each track where the Rickyness shines through moreso but they really sound similar and both sound awesome especially played by the legend himself. Geddy Lee.

 

If you put the J pickups in the Ric spots, it will take on more of that deeper, fundamental Ric tone. Same with putting Ric pickups in the J spots--you get more J burp. Of course this is an oversimplification, but pickup type and location go a long way. The settings on the amp take it further.
I have a Peavey Patriot with an added neck pickup. They pickups are agressive single coils located in the 24th and 36th "frets." This bass sounds like a Ric, despite having an alder or poplar body.
My Foundation with the same pickups in the J spots sounds more like a Jazz bass. This one must have a maple body, it's really dense and heavy.

 

I believe the Gibson "big bottom girls"-- Ripper, Grabber, G-3 -- all had maple bodies.