^ If mine moved that much I'd be pretty annoyed. It's obviously fairly light. Trunk's skinnier than I like too. Basically you're trying to emulate an opponent, so for me an 11" trunk is still much skinnier than me (even my waist ) but it was still workable to lift and woodwork.
You could always approach a semi-retired woodworker and ask how much to make one for you? If you supplied the materials etc. Like I said, secondhand wood (all of mine was recycled housing timber) and a raw trunk from a timberyard (cheap because they don't have to process it).
Or yeah, just choose a commercial one. I'm sure there are plenty in the U.K. Ring up some kwoons and ask where they got them from. My school resells the ones we use, or a bunch of students have just made their own like me.
If you want to make your own it's really not hard, even for an amateur. But I understand if you're not confident to try, it's a big job. Not hard, just lots of measuring and lots of hand labour. IMHO though, the end result of making your own is much more satisfying than buying one. Logistics could make it difficult though, e.g. if you lived in a flat in central London or on a second story floor.
Lastly, if my choice was frame or base I'd choose frame unless I didn't have the space. Occasionally you want to tread close to the base of the trunk (e.g. practising throws, sweeps, etc) and if it had a base that stuck out from the trunk it would annoy me.
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