Lots of possibilities and factors at play so don't quote me on my estimates - depends if gliding into the wind, having a tail wind, etc., also if the prop. is windmilling, has stopped entirely, engine at idle, and so on. Stall speed for a Bentley-powered Camel is about 48 mph (77 kph) - possibly lower for the LeRhone and Clerget-powered ones (oh let's say about 45 mph). The general rule of thumb is that glide speed is determined by weight of the aircraft (more weight requiring a bit more glide speed...).
Better to aim for the "minimum sink speed" as it's sometimes called, when trying to determine the best glide speed (min. sink speeds, as far as I know, are not published even in modern flight manuals - and require experimentation to figure out).
Based on my tinkerings with flight models in FE2 (and also in WOFF) - try gliding about 2-5 mph (about 5-10 kph) faster than when you start feeling that the airplane is beginning to stall. For the Camel, this puts us somewhere into the 55-59 mph range for glide speed (Bentley), about 52-57 mph on 110 and 130 hp Camels, and - taking a "guesstimate" here - about 50-53 mph on the Pup (since it should be somewhat lighter than Camels of any engine mount).
There are complicated formulas out there to figure out best glide speeds in relation to air density, wing loading, weight, drag, etc., - but it largely requires experimentation to figure out minimal sink speed.
Non-mathematical rule of thumb: to clear as many bushes and trees as possible before setting down - hopefully not in more bushes and trees. Aim for farmers' fields, meadows, or maybe a road - I should try out some dead-stick landings in WOFF one of these days as a rough experiment for glide speeds. Have had to dead-stick the Eindecker (E.II) a couple of times in my casual campaigns - the monoplanes tend to wallow and stall abruptly. Biplanes should be better at gliding. Will maybe experiment with how the Dr.1 and Tripehound behave when gliding with engine off.
Happy flying all and a Happy New Year as well,