Is it possible to have two products offered to the customer, but they can only purchase one of them? That is, they cannot order 1 of SKU 01 and 1 of SKU 02. If they put SKU 01 in their cart, they cannot add SKU 0002. If they remove SKU 01 from their cart, they can add SKU 02 to their cart .. and visa versa.
I found a forum post on here that says I can limit the quantity WITHIN SKU 01 and SKU 02. Either/or Radio button option? Of course it needs to tell the back end which product was chosen and separate shipping rates apply, so SKU 02 cannot merely be a variation of SKU 01.
Obviously this is contrary to wanting to sell lots of items, but it is due to a special promotion.