If you are thinking reclaim also think of a reclaim tank and the size and location you would need for that. One thing to keep in mind, with 550g and 8 gpm you will only have a couple hours (3-4 max) of water on board. I don't know your water situation at all, but for me I only have access to 6 bulk water fills in the entire city and when a few water trucks are in line in front you can have a 2 hour wait. 2 hours is fine at the end of the day, in the middle of a job though it can wreck a day fast.
If I was you I would do the water tank, 8 gpm pressure washer with heat, and hoses and stop there until you have made some money or landed some accounts. That alone will require $8-10k I figure, adding more on speculation could be good or could be bad. I have seen many guys spend big money outfitting a truck only to see it on craigslist 6 months to a year later as they could not find any work for it.