could the post WWI border between independent, capitalist Finland and the USSR have been drawn more favorably for the latter? Encompassing all of Lake Ladoga in USSR and having a greater hinterland for Leningrad?
If the border were like this, might Finland’s neutrality remain undisturbed in the 20th century, with no invasions across the Soviet-Finnish border?
Your assumption seems to be that the border's closeness to Leningrad was a real problem, not just a justification for Stalin to mess with Finnish sovereignty. As the Finnish participation in Barbarossa IOTL showed, moving the border 200 km west from the OTL 1920 line would not stop Finland being used as a staging area for an attack against the USSR if Finland allies with a major power or alliance that is hostile to the Soviets. Moving the border incrementally west will not stop Finland being a threat by proxy. The only thing that really removes this potential threat is moving the Soviet border to include Finland entirely inside the USSR.
This said, there were some who in the OTL border negotiations supported a border that would have given more of the Isthmus to the USSR in exchange for Finland getting significantly more land in Eastern Karelia. This border, reminescent of the borders negotiated between the Finnish Reds and the Bolsheviks in 1918, and the Terijoki government and Stalin in 1939/40, was supported for example by Rudolf Walden, Mannerheim's close confidante, on industrial grounds to gain more forest to be used by the wood industry. The thing is, though, that in 1920 the general Finnish views supported (rather unrealistic) hopes for a "Greater Finland" and in nationalist circles people even saw getting
only the OTL borders as a humiliation. It was therefore politically unlikely for the Finns to accept borders that are significantly less advantageous than what was agreed at the OTL Treaty of Tartu.
The only way to get borders that are worse for Finland would be if the Soviets are negotiating from a position of real strength, which in 1920 after the devastation of the Civil War and the Red Army's loss in Poland was unlikely. But then if we get to a situation where the Soviets are strong enough in 1919-21 to force borders like the post-WWII ones on Finland, losing so much territory with majority Finnish population will be seen as a true travesty and humiliation by the Finns and that kind of a border deal alone could make Finland in the 20s and 30s into a deeply revanchist state that (barring butterflies) joins the Nazis much more enthusiastically come a German attack against the USSR.