Most daysailors carry a portable, hoping not to use it, but it's good to have. Because it may not be used again for a month or more, it gets dumped and cleaned every time. In the winter, water must be exchanged for glycol.
On the other hand, what if you simply line the bowl with a wag bag? They contain a powder that stabilizes the mess, they zip-lock up tight, and you pitch them with the rest of the day's trash. I've only used them a few times, climbing above the tree line in parks where they were required (Tetons).
Honestly, it seems like an easier option, for a about $1/use. This, by the Pardeys:
http://www.landlpardey.com/Tips/2006/March.html
On the other hand, what if you simply line the bowl with a wag bag? They contain a powder that stabilizes the mess, they zip-lock up tight, and you pitch them with the rest of the day's trash. I've only used them a few times, climbing above the tree line in parks where they were required (Tetons).
Honestly, it seems like an easier option, for a about $1/use. This, by the Pardeys:
http://www.landlpardey.com/Tips/2006/March.html