I agree ... even for a single fixture, the use of a lift of some sort beats the dickens out of scaffolds and ladders.
Scissor lifts are great, but it's amazing just how little 'crown' in the pavement will set off the 'tip' indicator on them. Getting the scissor back on the trailer is also fun.
The best solution for me has proved to be a towable boom lift. Cost is an issue ... around here, renting one costs about $50 more than the $130 needed for a scissor lift and trailer combo. You also get to invest in a harness, if you don't already have one.
Yet, for that extra cost .... it's easy to visit a number of sites, and the boom will usually reach quite easily over and bushes or set-back the pole may have.
It's not just a matter of climbing. As the picture shows, the lights are usually set off from the pole. You need some place up there to place your parts .... and some of those parts are a bit heavy.