Trivision only works when you have a location that is so hot that everybody wants to be on there, and will pay nearly as much for a third of a billboard as they would for 100% of one. For example, if a billboard rents for $1,000 month as a "static" unit, then you need a location so hot that an advertiser will pay, say, $800 for one trivision face x 3 = $2,400 per month versus $1,000. Where you get in trouble is when you put a trivision on a billboard that is not very exciting, and you end up renting each trivision face for $400 x 3 = $1,200 versus $1,000. Remember, trivision costs extra to install the ads and in electricity -- not to mention the upfront capital cost -- so you need it to generate significantly more revenue, not just a little or no increase.
As far as 10,000 traffic in a small town -- if the unit is a head-on, curve-iin-the-road visibility in a great location, it might work. But do some market research first and make sure the demand is there.