What difference does it make if he stands up during ardaas and his hands are higher than the "chandni" ?

And perhaps some people can't afford more than just a little table with four small legs.

I remember when I was young, and we lived in a run-down apartment in New Jersey we had no table at all. We had a 15 inch tv on the floor and we would put the Guru Granth Sahib over it, and my mom used to read from it like that. My cousins could have donated a table over to us, they could have even donated a pure golden table to us, but would it make a difference?
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/sikh-sikhi-sikhism/1241-respect-guru-ji-guru-granth-sahib.html

And if you say, but Akhand Paht or other gatherings weren't performed there, what difference does that make? We used to have cousins and still read from the Sri Guru Granth Sahib Ji like that.

Is that beadbi?

The campaign of "respect to Guruji" is to stop INTENTIONAL dishonor to Guruji. Such as taking the Sri Guru Granth Sahib Ji to locations and having people dance around it while holding beer. That is intentional and known.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=1241

As far as someone standing up and the chaur sahib slightly over the "chandni" thats not intentional, I'm sure no one attempts to do that as to say their higher than Guruji.

As far as the space, can't you kindly talk to the owner of the home to create more space? I'm pretty sure they wouldn't mind that much..