Tuba for marching

[claf]

I will have to do some marching with the wind band I recently joined on tuba.
It will not be long marches, but something like 20 minutes of playing while marching almost the same of playing while standing.

While I could just use a harness for my Eb, I'm also thinking about buying a "cheap" helicon or sousaphone.
The sousaphone is the default choice, but I think it will be easier to go for a helicon (lighter, easier to manage, better for my back and my neck).

I could get any key (except F, I don't like F), but lean more towards Eb (more readily available for cheap).
3 valves should be enough, 4 valves would be very nice.

What is you opinion on this subject?

Also, would it work with an instrument such as this one? Are these soviets horn playable, more or less in tune and tunable to a standard 440?

[claf]

Forgot to mention, my current "no need for investment" plan is to use my bass trombone. Not ideal but would do the job.

[gocsick]

Eb Sousaphones can be picked up cheap. I paid $300 for my Holton. They just take a little while to show up.

I was also given a random stencil Eb sousa by a middle school band director. They received it as a donation and figured it out was Eb after the fact. I changed out the receiver so it took a King or Yamaha neck (I didn't remember which) and passed it into a young student who wanted to learn Eb for brass band with the instruction she give it to someone else when she was done.

[claf]

I would love an Eb sousaphone, but it's rarer than hens' teeth in Europe...

[gocsick]

Ahh my assumption that everyone is from the US rears its ugly head again.

[claf]

No problem, you are probably true most of the time in here