I am surprised you cannot get any daytime QSOs?
Which bands are you trying on?
I would have thought there would have been some bands open eg 14MHz, 18 MHz and 21 MHz?
Part of the problem is that my location (south Thailand) generally precludes QSOs in the < 500Km range because there are no other active hams - I need to have a daytime QSO range of 500 - 2,000Km.
I listened on those bands around local midday today. I could hear 1 Chinese ham (in Chinese language), but none from Thailand or neighbouring countries (and have never heard these in the daytime).
The nearest country where I have regular QSOs is across the Indian Ocean to India ==> 2,000Km.
Evening is a different affair, with QSOs from Brazil via greyline, and daily to Europe, Middle East, Australia etc. Evening on 40m I hear stations in Malaysia and Indonesia.
So it isn't really that my mobile set-up is 'poor'. My need is rather to absolutely optimize that set-up to enable daytime 1,000km QSOs.