The Ritta Nakashiki book only includes one example of a Tosa Domain soldier, though probably not an ordinary private as it includes the red version of the 'bearskin' headgear worn by NCO and officer equivalents in Satsuma and Choshu domains. In it he wears a single-breasted, dark-coloured shirt with a high collar and tucked in at the waist, boots rather than sandals, and one sword rather than two.
I don't know how far this style might be extrapolated to ordinary privates, and it doesn't seem to have been very standardised, given the variety of clothes seen on display in this photo of Tosa troops:
What's interesting is that there is one contemporary illustration showing an entire contingent of Tosa troops, supposedly identified as the Jinshotai, wearing red Shaguma headdresses at the Battle of Ueno in July 1868, with only a few men (officers perhaps?) wearing round Jingasa helmets:
This could just be fanciful though, as this other illustration shows most Imperial troops wearing either Nirayama-gasa or kepis, while only two or three men wearing headdresses lead a charge across a bridge, which would be appropriate if they were only used by officers:
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And a similar scene is depicted here, with a lot more colour variety in terms of shirts/jackets:
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This dramatised print seems to show a variety of headgear on display by the presumably-Tosa forces, who are shown largely in red shirts:
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This image shows red-jacketed, kepi-wearing troops under the imperial banner at Ueno, but may not be Tosa:
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And finally this shows what may have been Tosa troops (assuming that the red headdress was exclusive to Tosa) at a skirmish in Rikuzen, with some men in blue shirt and trousers, some with a red outer jacket and white trousers, and almost all men, save the headdress-wearing officer, wearing what look to be round Jingasa helmets.
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Probably a reasonable inference might be as follows:
The 'ideal' uniform for Tosa 'privates' (or equivalent) was probably a Prussian blue or black high-collared tunic that would be either tucked in at the waist or hang over the trousers but under the belt; there would be a cartridge pouch on the right and sword on the left held by crossbelts; headgear is uncertain but was probably either a kepi or a round Jingasa. The red headgear would be worn by officers and probably NCO-equivalents.
In practice, however, there would have been some variation. White trousers seem to have been a common substitution during the summer months, and Tosa in particular might have issued red jackets to go over the blue tunics, but which were worn only optionally. In addition, the red headgear might have been worn more widely, perhaps by elite elements like the Jinshotai, but this seems to be attested only in certain depictions of the Battle of Ueno.
