My suggestion would be make a DBA or Scorp and state they are 50/50 then use the company to take a loan(interest rate would be higher ofc), that is if both of them knows how business work. If your husband is not so serious about making this work, as others said, take a check is far more safer.
A Doing Business As won't really help in this case. Opening an Scorp, brings it's own can of worms. Just meeting the requirements is a huge headache. That's why so many business converted to a llc. But in this particular case I don't no. Once again I say you have to first no, then run your numbers. Then things like who takes the depreciation who deducts the fuel, repairs etc? All that has to be worked out. But it's all in the numbers. But don't over think and complicate it, it's not that difficult.