instead of a long complicated process to pre-empt corruption, just have an automatic and detailed post-award review for corruption. Corruption discovered in the review is referred for criminal prosecution.
After the first 500 or so corporate CEOs and executives are jailed, the rest will get the point. Offer your best price, compete with your competitors, sell your offer on its merits in the open bid, and stay away from the bid evaluators and other potential or actual bidders.