I can't tell you what size to buy but I can advise on the bike. If you tie it "down" you're pulling pressure on the fork and shock seals while tied. Not a good idea for long term. I installed some railing from Northern tools on the sidewalls. I cut a 2x4 that goes from side to side of the trailer and fits in these brackets that latch in the side rails. Then I installed eye bolts in the 2x4 and tie the bikes forks to those eye bolts. I also strap the tires to the floor. That way there's no pressure on the fork seals.
I tow two bikes, a Versys 1000 and a Honda NC700X (one forward and one backed in) plus a tool cart that mounted to the floor, Trailer dolly and a small air compressor. Then all the extra RV stuff like chairs, tarps etc are mounted to the walls, ceiling and doors. That's all in a 10 footer!
V nose trailers are nice. Look for LED lights and rear ramp door. The big box stores sell them but better deals are out there. Craigslist is a good place to look.
Upgrade the tires! Most come with **** tires.
Also rear legs are nice so you can load and unload while unhooked. Otherwise the trailer does wheelies when loading. Might ever take off rolling on you.
