Gehyra species have rounded toe pads and lack a claw on the first digit. Your excellent photo shows this very clearly. Well done.
As stated it is G. dubius. As a generalisation applicable to all G. variegata, the pale markings on the back are in contact with the dark markings (bars or streaks). Note that this is not the case with yours. There is also a difference in the lamellae under the toes, with G. variegata divided and in G. dubia are at best deeply notched but undivided. The overall patterning on both species is highly variable and is often related to what particular part of the range they are in.
An explanation of why snout-vent length is used...
Most lizard groups have fragile tails and regrowth is often seen in a high number of individuals in natural populations. In order to be able to use all the data from collected specimens, especially where numbers are limited, it has to be consistent and so only body length is utilised. Body length is determined by measuring the distance from the tip of the snout to the vent, referred to as snout-vent length (=SVL). The tails of varanids are not fragile and so the data for them often includes both SVL and total length (=TL) i.e. from snout tip to end of tail, or even just TL on its own. TL is used with snakes for the same reason. Dragons are a bit like crocodiles. While their tails are not fragile they can often sustain a significant percentage of bites to the tail which shortens them. So SVL is usually used although data is often also given about tail length as a percentage of body length. This is normally done with pygopods, as the tail represents such a hugely significant proportion of total length.
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