Why not exclude NWC and account for extra $$ to save the pain of confusion?

I am negotiating an LOI at the moment, asset sale, $500k SDE for $430k. The $500k SDE is previous FY, $300k in previous year, breakeven 3 years ago, and stable $200k in prior years. 6 month order book predicts $700k SDE in next 12m.

It is a project-based engineering business with egregious add-backs, hence the discounted multiple. The owner is extremely financially unsavvy, to the extent that he doesn't have a handle at all on net profit vs gross.

I learned today that the seller assumes he will collect the cash on AR. The broker is not helping - he has the view that working capital is never included in asset sales. Even if the concept was understood, the practical nature of establishing the peg would be a nightmare given the month-to-month lumpiness of WC.

I have stretched negotiations thus far, and the current structure / price has room to account for working capital cash on close.


Questions:

1) What do I risk by excluding NWC from the deal and making an estimate on historicals, then accounting for that cash on close?
2) I assume I would need to somehow account for / look out for accelerated invoicing for projects in progress just prior to close. Any ideas on how to handle that?
3) I should push to accommodate inventory in the sale (which is predominantly WIP) because to tease out the partial progress from upcoming progress invoices would just be a mess. Or just wear it and take the risk? Thoughts?
4) A/P would have to be excluded, and customer deposits included in the sale (reduction in EV). Right?