Adding the ability to only show a percentage of available stock on a WooCommerce product page

From the research I have done it doesn’t seem like there is a plug-in available that extensively extends the stock section within WooCommerce product listings.

Situation: My client will have his products, they are not products that are high in demand but every now and again, there will be a wholesaler of some variety that comes on and buys the whole collection they have.

Issue: He doesn’t wish to allow someone to buy all of his stock in one visit. He wants to display the stock count, but only say there is 80% of the total. Leaving 20% sitting in the warehouse and for the next visiter.

Perks: This will allow him to make big sales, but when a smaller user comes along, they will still be able to purchase the product, or we could display a message to pre-order and the item will be shipped when the next delivery comes in later today.

Solution: One solution would be to reserve the final 20 products, while allowing the wholesale purchase of the calc(100% – 20) quantity of the item. The nail in the coffin would be to then limit the quantity allowed to be bought from the final 20 to a maximum of 5 in a single transaction. If this could also come with helpful messages displayed to the users like maximum of 5 available in a single transaction. Or pre-order and your item will be shipped later on today after the delivery arrives.

Plugins, documentation, solutions are all welcome, appreciate your time, J.