hi
ON Juno there were only four types of devices used, SBG, FASCINE carpet layer and a LOG Carrier used by 26 Assault Squadron.
when the LST opened its doors the Rolly Polly a another type of mat was pushed out from the bow doors , then a log carrier would push it till it ran out then he would lay the logs followed by a carpet layer .
The log carrier is a simple design; it had timber rails attached to the infantry rides and a tubular frame right in front of the driver to support the weight. Logs were just piled up on the infantry rides with the turret turned side ways. One such vehicle was driven by a friend of mine.
I found the plan with a friend of mine in the PRO but more over if you have D DAY vol 2 then and now there is a picture of one front on nest to a water fountain in a town complete with wading trunking.
Hope this helps, the picture is so small to actually ID the vehicle.
Some where I do have the loading lists for the LST on Juno.
Hope this helps
Ossie