heterologous gene integration into e.coli genome - (Feb/13/2013 )

Hi. I'm trying to integrate heterologous genes into E.coli genome.

The problem is that the size of the genes are about 7 kb.
The only system that I can use is a home-made suicide vector using R6K origin and sacB.

Several trials ended up with failures.
Do you think that 7 kb is too long to integrate into E.coli genome with this system?
Actually, I don't have any experiences to mutate E.coli. Please give me any tips of advice. (incubation time, cautions, troubleshootings etc.)
Thank you in advance.

I don't know anything about suicide vectors but while searching about this I found out a word document that is attached here. I thought it might be useful for you ..