The Deneb Light Cavalry is not, contrary to popular belief, composed solely of Light and Medium 'mechs; as such, they make a great 'generic' Davion force. They have a simple color scheme and their individual elements can stand in for any other AFFS regiment if properly chosen to represent a mixture of weight-classes.
From the available info we have, we know that at the time of the 4th Succession War, the 4th and 5th DLC fielded some heavy equipment indeed. The former's First battalion was composed of two Assault companies and a heavy company while the latter, in it is Third Battalion yielded a full Heavy company. The balance was split fairly evenly between Lights and Mediums in the 5th, while the 4th fielded five Light 'Mech companies and a solitary one of Mediums (source: 4th SW Atlas Vol. 1). The old FASA 4th SW Scenarios Vol 1 gave us a 'mixed-bag' company from the 5th DLC that fielded no less than four Assault 'Mechs out of seven (with a Heavy, Medium, and Light completing it).
As of 3025 (per the HDSB), the 15th DLC also "carries a fourth battalion of heavy 'Mechs". So, not all DLC units are composed chiefly of Light 'Mechs. There is room for all sorts in a DLC outfit. But I will admit, however, that they are known for using lighter elements and for that reason the initially pictured force is a bit too heavy for a generic DLC outfit. It also lacks many of the lighter AFFS staples of the period which is why I think "Davion mercenary" as opposed to DLC.
Now, could that be an ELH force? Sure, why not. Paint them olive drab and they can be 8th DLC in a pinch. My own ELH force is based around the premise of being able to portray them as seen in the original Mercenary's Handbook at a company level so I have everything from Locusts to Atlases.
Fun fact: if you want to build a force like that and be able to put a any company from the entire unit on the table, you only need 60 or so 'Mechs to ensure very minimal proxying...