I would highly recommend at least a 20ft trailer, 10K capacity as a minimum. I have a DK40SE HST (same size as the CT450) and if I have my FEL and brush bull on, I have to pull it forward and put the bucket down over the tongue of my 18 ft trailer. Like mentioned before, what will you be pulling it with??? If you can get a goose-neck, then you could possible set your bucket on the "neck" if needed. If you can, go for 22 ft.....you'll never regret it......I'm always wishing I had a longer trailer!!!!
Some other points/tips to think about and check out.....make sure you get brakes on all 4 wheels! Double check the tire size and load rating or your tires....if a 15" tire, you'll probably be looking at a 225 - 75 - 15 D rated tires.
If you get hinged ramps on the rear, be sure to get them spring loaded!!! Makes life so much easier!!! The springs should be b/w $22 to $30 add-on if not already standard equipment. I have a friend whose trailer had vertical slide pins to hold the ramps up.....the metal was too soft and the weight of the ramps bent the pins. I added on side bars (45 degree angle) for him and he's much happier.
I have a wooden deck....7 yrs old now and still doing well though I've not maintained the wood.
Hope this helps??!!