Hi DJW,
Just do it! I did my first big trip in 2009, and here a link to my lead-up and daily blog.
http://halfwayroundwithpete.blogspot.com.au/ Our plan was also to ride for a few days and then have a day off. You will find that the distances come easier after the first few days in the saddle. I started off with an Yamaha and came home with an ST1300. You will have plenty of room on the ST for a two man tent, sleeping mat and sleeping bag and all your other stuff, so my advice would be to leave the trailer home. Here's my pack list. This list has been refined and cut down after many long touring trips, as the mistake that any make when first starting out is to take far too much stuff.
Left Pannier holds my clothing, toiletries, chargers and torches etc, first aid kit, spare gloves and wet weathers.
Right Pannier holds tent, and shoes deck shoes and thongs. My air mattress and sleeping bag are in a waterproof bag on the back seat, and the rest of the junk fits in the
top box with lots of room to spare.
Cheers
Pete