Find out what it takes to convert the cargo van title to an RV title in your state.
Then you could qualify for an RV loan with the lower rates you are looking for.
Often times they are looking for a toilet, place to cook, permanent bed, every state is different.
Its likely this would have to be done by the PO before paying for the vans title.
In Idaho it looks like this,
(4) As used in this section, the term "recreational vehicle" means a motor home, travel trailer, park model recreational vehicle, truck camper or camping trailer, with or without motive power, designed for human habitation for recreational or emergency occupancy. The term "recreational vehicle" shall not include pickup hoods, shells, or canopies designed, created or modified for occupational usage. School buses or van type vehicles which are converted to recreational use are defined as recreational vehicles. Specific classes of recreational vehicles are defined as follows:
(a) The term "motor home" shall mean a vehicular unit designed to provide temporary living quarters, built into an integral part of or permanently attached to a self-propelled motor vehicle chassis. The vehicle must contain permanently installed independent life support systems which meet the American national standards institute (ANSI) A119.7 standard for recreational vehicles, and provide at least four (4) of the following facilities: cooking, refrigeration or icebox, self-contained toilet, heating and/or air conditioning, a potable water supply system including a faucet and sink, separate 110-125 volt electrical power supply and/or LP-gas supply.
(