My advice to you, is have the customer own their own dreamhost account. Do not try to own their hosting. For one its not profitable, and for two when they aren’t your client anymore it doesn’t waste one drop of your time (that you’re not getting paid for.)
Additionally it doesn’t put you in the middle when some dreamhost email server gets blocked somewhere.
If you want to make some kind of profit off the customers hosting then use the affiliates/rewards links from dreamhost. Frankly tho deals that are profitable to you thru affiliates/rewards cost the customer more.
To make a profit charge for your time, either by the job or by the hour.
Let’s me paint the all-to-often picture for you. Some time unit down the road customer stops paying you. They want more work, but you want them to pay for their hosting first. -Or- you cut them off for non-payment and they trash talk you for letting their site go dark.
Charge for the time or job, but don’t try to own the customers hosting. Let the customer have their own relationship with dreamhost. The customer can grant your account access to theirs, so there is no need to keep track of multiple panel logins.
That anywhere close to what your own thought were?