I never found fat tires to slow down a bike much. Fenders on the other hand ... I never had to worry about riding in work clothes since I am blessed with a workplace shower/gym. So I would take a nimble fat tire bike ...
The best description ... I am looking for the recumbent equivalent of a cyclocross bike. I will heed your advice regarding test rides. Luckily for me, there are two shops in the area with excellent reputations for recumbents ...
www.bikesatvienna.com
www.bike123.com