Two issues from a newbie... :-)

Would be a kewel mod to use a different rear master and de-link the brakes. Would have to change front calipers too me guesses. I use the rear brake exclusively under riding situations like a roundabout or petrol station fill ups. Otherwise its just front binders, rear brakes last the life of the bike. Changed mine around 70,000 miles. Cheers. btw I always use steel braided lines for the brakes on all my bikies.