Hi Mate,
First thing to check is that there was recall on the gas caps in Jan 2013 because of a gas smell after a ride (just like you're describing). This should have been replaced on yours already but it's possible it's not. Mine was supposed to have been done by one dealer but when I took it took it to another dealer they found it hadn't. Now the only problem with this is that the replacement may have another issue but it does stop the gas smell.
The second thing is the canister that's supposed to vent the tank. Sometimes petrol can soak the filter in the canister which leads to a strong petrol smell. This can happen if you 'overfill' your tank but as you probably know that's hard to do on a Spyder. However I also had issues after long drives and the problem went away after I did a 'Canisterectomy' and removed it. If you search this site for 'Canisterectomy' you should find plenty of instructions on how to do it. As you mention a tube this is the more likely cause.
On the gas cap side - even if you have the post recall gas cap it has a problem with getting stuck so you may want to consider ordering a Stant one instead:
http://www.ebay.com/sch/i.html?_fro...0.XSTANT+10819.TRS0&_nkw=STANT+10819&_sacat=0
PS Where in NZ are you?