Mod sled build questions

I'm new to this whole thing but I'm looking at building a sled.

My plan is to start small, at least power-wise and try to build up a light weight trail/boondocking sled for where I live in North-Eastern Alberta.

A big part of this decision is the sled I have now, an '07 Phazer Mountain Lite. It's okay but _heavy_ and I'd like something a bit more playfull. It tops out at ~125 km/h on groomed trails, around 100 off trail if the snow isn't too deep. The speed is more than enough for me, I don't need anything faster.

It's been in the planning stage for a while and I decided on an air-cooled ~500cc motor with a 16x136 track to give enough area for flotation but a shorter track for trail handling.

I figured geared to top out around 100-120 km/h (~60-75 mph) the 50 or so hp from a fan-cooled motor should give decent acceleration (I don't mind the lower top speed and gearing it down should make it accelerate well which should make it feel fast for the speed most riding will be at).

I finally committed to buying the first piece (actually first and second, I bought two Mikuni power-jet kits for the carbs) of the build last week so the project is officially started - A Polaris 440 fan motor complete with carbs, y-pipe, recoil starter, fuel pump, and primary clutch. I got it for $300 Canadian, supposedly it runs. I'm going to open it up and look it over, rebuild the carbs, fuel pump, etc. I'm thinking I'll weld up a pipe for it.

Now that the build has officially begun and I have some fact checking to do and questions to ask.

1 - I've been doing research and it looks to me like 2024 0.05" sheet aluminum is appropriate for the tunnel?

2: Clutch spacing - is there anything I should be aware of as far as setting up the clutches? Obviously putting them 5 feet apart or something equally ridiculous is going to make it impossible to get a belt that fits but is there some magic number I should be aiming for in terms of separation between the two clutches?

3: CVT belt part 2 - Once I get the clutches installed and aligned how do I choose a belt that fits?

4: Rivets - Solid aviation rivets, not cheap hardware store rivets are what i want I'm guessing?

Agreed on the long road before getting to setting up the clutches, that said it's the kind of thing worth planning for in advance to avoid finding out later I don't have room for something.

I'm thinking of going with a-arms for the front suspension. That's the hardest part I think, everything else is pretty much pre-designed for you and ready to bolt on. designing the front of the chassis to mount the a-arms is more difficult.

That's an idea... Darn, more to think about! ;-)