In truth, you'd be better off starting with a Vulcan 500, as they are already halfway there, having an easier modded frame and fat rear tires. As to fat front tires, this is art over design, as they ruin handling. Even the 180hp BMW R1000RR only uses a 120 section front tire. Studies were done back in the 80s regarding front tire size. Since there were so many cases of racers losing the front end, a few tried fat tires. Made it worse. Messing with wheel diameter and most of all, stickier tires was the solution.
If you are a slow-sped rider and just cruising the beach, bobbers are a reasonable style. Most guys do street fighter/rat bikes or cafť racers.
If you want ideas, check Google Images for 'EX500 Bobber' and see what turns up.
I finally figured out why I like Ducatis: With their exhaust note and dry clutch, they sound almost like a Guzzi!