Reserve a place to park the van.

Choose the most crowded place in your community to park the van.

Have flyers with church's address to share with people.

Have volunteers to invite people to come inside the van.

Have volunteers to do massage, if you are expecting a lot of people.

Have a follow-up evangelistic program such as health classes, bible classes, evangelistic meeting, small groups, etc. 

Have flyers for these evangelistic meetings.

If the van breaks, the request may be canceled.