Any particular reason you're looking into this? I doubt you'd be able to specify the trailing length of the tubes; the front extends by some percentage of tube diameter.
Bottom line, the builder will have a LOA based on their design; doubtful you'll be able to change it.
As far as selecting a boat, that's not something I would look at; material, layout, shape, Vee angle, etc would be much higher on my list.
jky
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