Baby, I'm Yours by Susan Andersen

Sam McKade is a bail enforcer/bounty hunter and a chance glimpse of a woman he recognizes in an airport leads him to follow Kaylee MacPherson to Seattle, knowing that she is out on bail and violating conditions by leaving the state of Florida.  Only when he catches her at her sister's house she claims she actually is her sister!  Sam knows that Catherine is supposed to be in Europe though, and besides he checks that she's got the kissy lips tattoo on her ass like she's supposed to.  So he hauls her off to the greyhound bus station for a several day ride back to Miami - he would normally fly but he's on a budget: he needs this bounty to have enough money to make the downpayment on the cabin he wants to buy for his friend Gary who is now wheelchair bound after a shooting incident when Sam was the noncomm officer in charge for the military police, leaving Sam wracked with guilt. 

Catherine is totally not thrilled of course - first her European vacation gets ruined as her travel agent went bankrupt and stole her vacation and then she gets Sam and cannot convince him that she's not Kaylee.  Stuck with a suitcase of her sister's tight showgirl clothes and several days of greyhound bus travel to look forward to, she decides to make as much trouble for Sam as she can, getting them kicked off several buses and having to stay in motels for a few odd nights.  Meanwhile the reason Kaylee skipped bail in Florida was that she overheard the owner of her nightclub ordering Jimmy Chains to kill someone...her boyfriend Bobby LaBon who works as a bouncer under Chains flys to Seattle to find her but Chains is also following them, only he thinks Catherine is her, cuz she never told anyone about her sister.  Can they all get out of this mess?  Will Sam ever believe Catherine is a teacher for the deaf rather than a showgirl?

Yup - this is a fun book.  Sure it's all highly implausible but it's a great time.