It depends how long the jouney is. I would think that from Michigan to Mexico, you would be able to irrigate before you go and still have plenty of time spare when you get there before you need to irrigate again. I know some people can go two days between irrigations but I need to do it every 24hours, or at a push I might last to 36hours. The journey from the UK to where I want to go in NZ needs plane changes so can sometimes take all of that and more. However, I use a pressurised water system rather than the gravity feed one usually supplied, so I don't have problems with finding places to hang the pouch as my supply of water sits on the floor and is pumped in. This means I can either do it on the plane or in the transit lounge on the long journey.
For information on a pressurised irrigator see the Braun Irypump. www.bbraun.co.uk
For an overview of their previous 'irridrain' pump, you could look at one of my old blogs, where I wrote a review.
Alternatively, if you cannot afford their top-of -the-range system, you could make your own pressurised pump like I did - out of a garden sprayer and a Coloplast cone which has a hand held adjustment arrangement. It has worked perfectly well for me for years and as my new pressurised container is short and fat, rahter than long and thin like the old one, I can stuff it full of other gear while it's not in use. Very handy when you are travelling!
Many people travel with a stoma and don't have too much of a problem but I would take heed of what Manina has said about the water. Although, I've heard some awful stories about some bottled water being simply obtained from local sources, whichwould mean that you are no better off using them than you would be getting it out of the tap.
Never let your stoma hold you back from doing what you want to do.
Best wishes
Bill