The images below show from the Topps trading card series show Solo, Val and Beckett all dressed in the Mud Trooper uniform. There are echoes to uniforms in the Original Trilogy - the cap on Beckett's head, the colour is the same as the Imperial officers, the cut is very East German etc etc - but the thing that really got us was the helmet that we see Solo and Val both wearing.
Although the mask (left) is certainly reminiscent of a simpler form of Stormtrooper helmet, the helmet itself is very reminiscent of on General Veers (below) - even the signature goggles are similar. Team the helmet up with the breastplate and we have a direct link between Solo and Empire Strikes Back. Veers uniform has always been a bit of a mystery, but it works in with a theory...
The Imperial Navy have troops - we see them on the Death Star dressed in black (below) - so are the Mud Troopers in fact what the Imperial Army looked like before the widespread introduction of Stormtroopers?
Rogue One takes place at least a decade after Solo, so evolution of the armour would make sense, as would the phasing out of specialist Stormtrooper roles as the Empire amalgamates into a more harmonious military machine.
The big question we take out of this is does General Veers wear an Imperial Army uniform when he takes to ground combat AND is there any link to Dengar the bounty hunter's costume (below left)? \
Dengar does have an important difference, he wears the leg and lower arm armour of a Stromtrooper, but his breastplate is certainly very similar to the Mudtrooper or even the Snow Trooper (below right).