Log long HTTP URL LTM

I have reviewed several of the other devcentral posts about HTTP HOST length on LTM but I'm still not quite finding the answer I need.

I am using SSL termination and a sideband call to load balance customer requests to a Splunk server. One of the splunk URLs has a search param that creats a URL ~14,700 chars long! The customer's browser (believe Chrome or FF) handles the call fine when going directly to the server but fails through the F5.

The F5 appears to be truncating the URL at ~990 chars, which makes sense considering the 1024 bytes limits on irule syslog facility. However, I need to send the full URL to the sideband server. I believe I am capturing the full URL because

log local0. "URL Length: [string length [HTTP::host][HTTP::uri]]

returns a value of 14748. How can I chop up the URL to get the remaining chars and recompile to send on? Is this even possible?

Thx