How to run constraint rules on workbench

Summary:

Dear Team,

How can we run some constraint or valudation rules on workbench. Our usecase is that user needs to select bulk assets (3000-4000) for renewal but this might impact performance a lot hence if they have selected more than 50 assets and clicked Renew action then a validation rule should fire throwing message to constraint the num of selected assets to 50 at a time.

Another question is when user clicks on customer assets action it takes to workbench with unfiltered assets view for an account. Can we customize the workbench navigation link to show filtered list of assets based on certain parameters. Any examples would be helpful to achieve this.