Custom user title by product owned

[ncangler]

Hi all. I'm wondering if there is an easy way to add some custom fields in a user profile that would then automatically choose a custom user title for a registered member. I have a boat forum and would like to enable members to choose a title based on the model of boat they own, from a list that I administer. I thought if they could choose their boat model during registration (or by going to their Options in User CP if already registered) and it would automatically assign a user title to them it would be a nice enhancement to our site. I could see this same idea working for many different forums that are product based. Any ideas? Thanks for any input.