Carport structural question
If your question is:

&quot;Can a lean-to shed be designed so that it can be supported with 3
posts on one side and only two on the other?&quot;

Then the answer is yes, it can be done.  Is it too &quot;risky&quot;?  Too risky for what?  To support the expected snow and wind load?  The answer to that is:

&quot;Yes, that too can be done.&quot;

I suspect, however, your real question is:

&quot;HOW do I do this?&quot;

The answer to that is:

Seek out some pre-designed plans for such a structure that will be acceptable to your local AHJ to obtain a building permit.
Get a design done for you by an architect or a licensed engineer that has been analyzed to support the expected loading in your area. (The AHJ will want this when applying for the building permit.)