Hi Mike, As suggested, there's plenty of scope for creativity in making a "convertible" set up, from float-legering to quick-swap arrangements.
If I'm guessing right, though, you're thinking of fishing the Dane, and there are a couple of reasons why it's hard to come up with a satisfactory way to make one rod with variable end tackle cover what you need on that river.
Usually, stick float approaches aim to catch mixed small to medium fish, typically a mix of grayling (the higher upstream, the more of these), roach, dace and chublets. It works best with lightish gear, light line and small hooks, such as 2.5lb line and size 18 hooks. The fish come to your loose feed, and you're catching just a few yards down from your rod end. As Mr May was doing in that video.
Legering, unless for barbel , is usually aimed at chub, and needs a heavier set up - as much as 4-6lb line and a size 10 hook for bigger baits like bread.
The chub don't tend to come up close like the smaller fish, and you usually find yourself fishing a leger, or very small feeder, down your swim to a feature or down and across the river to the far bank.
The upshot is that while you can take your float off and improvise a leger from it, it wouldn't really be right for the chub - perhaps just a less efficient way to catch the smaller fish, which can become harder to catch on the lead.
And going the other way - adding a light float to your heavier chub set up, wouldn't make a a good small fish set up.
Sorry if that's a bit long-winded. But I found I needed two rods if I really wanted to do fish both ways and not be too compromised. But my Dane leger rod was a lightweight 9' job with a small reel, so taking it along wasn't a big chore, and the rest amounted to a bag of liquidised bread, a few slices for bait and 3 or 4 little cage feeders.
There is a third way; once you get to know the stretches, you will find there are swims where the chub can be caught in open water on the float, and then you can just beef up your stick float gear a bit. But by it's serpentine and delightfully overgrown nature, in a lot of swims the chub are hooked by the snags.
It's a lovely river, and for all that I'm surrounded by them here, I miss fishing it.