Battling nmap options

Finally starting my lab time for the Backtrack training and have been experience quite a bit of funstration as a result.

Access to the lab is via an openvpn connection and as a result there are a couple scanning switches that I'm gradually realizing are becoming my nmap friend. Using nmap 5.35 for nmap scripting goodness. Very quickly:

--send-ip
I haven't looked into this in great detail but without this option it appears that nmap may be assuming that another ip address in my subnet is close enough to default back to an ARP scan. As my connection has a high latency coupled with the VPN access I've been battling a number of my scans failing to detect an online host even with the -Pn option.

--host-timeout
Looks useful for scanning through the range while letting slow hosts not tie down the scanner. My initial attempt at letting a scan run through the entire range hung so this option should let the scan carry on and skip hosts that cannot complete in a given timeframe.