Can't help on the tires other than to guess you will likely have to use 2 brands to cover both sizes with dual sport/ADV tires.
PBI sprockets has a 16 tooth front which would give you a bit more dirt jerking ability over the stock 17.
There are lots of rear sprocket choices out there, but few front with the correct offset so I thought I'd mention it.

 

Stop! you're bringing back (somewhat bad) memories of my 650 BSA in the dirt, (which turned out to be an overweight, under-suspended poorly geared choice,,,) Eventually sold it to a guy who made a cafe racer out of it. I'm thinking the RS may be the same. However, If you're doing it just for the look and staying on the street, then go for it.

 

I
I already take it on the dirt all the time. Sliding around and struggling with a heavy bike lol. But its certainty not optimized for it so im going to make it a little better offroad. Besides, let a buddy ride it and he crashed so the resale is kaput.

 

You can find front tires from several manufacturers but you might need to go to a 17 inch wheel in the rear to get an enduro/dirt tire. Shinko 700 and 705 look like they would work but again, you would need a 17 inch rear wheel. Good luck and I will be following along waiting on your progress reports. 👍

 

I would think a heavy bike off road is a bad idea. I don't feel good on mine anyway.
BUT, when I see these guys I guess it can be done.

Funny seeing things flying off.

 

WOW, that just shows how durable these darn Honda's are.

 

The best 16" I could come up with and it is a bit too narrow and not great ratings, but better than the Bridgestone one, the rest of the 16" seem to be crazy narrow. Duro HF903 / HF904 Median Dual Sport Tires | 26% ($30.51) Off! - RevZilla

17" would get you more choices or maybe go Darkside and pick a snow tire, although I can't condone such horrible, dangerous activities.

 

We're gonna need some pictures of this thing. Sounds like an awesome project.