YA book, read in the 90s involving 3 children who whilst fleeing from the consequences of shop lifting are lured into an RV to hide. Spoilers ahead.

[Jack]

They’re then kidnapped by either a man or a couple and taken away. Eventually there is conflict between the two boys over the girl. Then they escape and get back to their lives.

[Rainbowheart]

Hideaway?

[Mary]

https://www.goodreads.com/en/book/sho...
The runaways?

This is about two kids who find a bunch of money in an abandoned building and run away together. There is a scene where they stow away in a caravan?

[Kris]

Worldcat.org description of Hideaway by Ruth Thomas - Rainbowheart's description:

"When Jack, Leah and Charlie find a bag of jewels in George and Lil's camper van, the thieves kidnap them and abandon them in the countryside, before making their escape. From then on, the children must rely on their own resources in order to survive."
https://www.worldcat.org/title/hideaw...

[Kris]

Google Books preview of The Runaways by Ruth Thomas- Mary's suggestion:

https://books.google.com/books?id=nSd... There are different cover images.