The subject of spacers was beaten to death long ago. Common knowledge with this machine that if you go up you have to go out, otherwise it's a pucker fest...period. We came off the high dollar for some taller more aggressive tires, then choose to keep them in handcuffs?
We all bought these machines with the 50" restriction in mind but a couple of inches isn't going to matter much unless you're riding where they have trail nazi's with tapes. Even then, the risk of tipping over out weighs the risk of a ticket.
Then there's the concern of stress on the drive train. Many have added aftermarket wheels and/or spacers and put it through it's paces for years now and it's proven that it'll take it. And again, benefit out weighs the risk.
There's not many things left on the P5 that someone hasn't been there done that and a handful that the consensus says makes the biggest difference in the ride...
Bigger better tires...preferably radials.
Spread the stance...preferably offset wheels but spacers work too.
Disconnect ASB...it's free.
Better shocks...expensive but worth it.
Don't mean to preach but with each one of these modifications you'll say 'wow, it's a different machine'.