another option i have done a few times in the past is a secondary button (insert technical stuff here) you have to push the button and then start the vehicle at the same time. so for push button start, you have to hold the secondary button while pushing the start button. vehicle wont start without that process, yet anyone looking at the button would have no idea what it does. usually its under the dash hidden, yet easy to access. you would lose the ability to remote start the vehicle, however an aftermarket alarm system can work with it