CMM4 GPS Antenna Coaxial Cable Length

I was reading the CMM4 manual, and it states that the cable length from the CMM4 to the GPS antenna must be under 30 meters.  This has not been a problem for us in the past, but we  have  a water tower that has no exit under 100 meters.  They will not allow us to drill a small hole in the side of the tower, and it does not fit in between the door opening.  What are people doing when they need to go to the  top of a tower that is  greater than 30 meters?  

We have never had to run one up a tower, generally just outside to the roof somewhere so it has a good view of the sky.  Our longest run is probably 20 meters.  I would think that, like any other IF with DC cable run, if you want to go longer distance, just increase the size of your cable, thereby decreasing loss per meter.  If I was going to do a run over 100m, I would probably go with LMR-600.

That said, are you running your GPS antennas to the top of towers?  Are these CMM4's indoor units?

We are using the CMM4 indoor unit.  The plan is to put the  GPS antenna on the top of the water tower.  The  total cable run will be ~90 meters.  Thanks for the suggestgion on increasing the size of the cable.

What are your reasons for wanting the antenna at the top of the tower?

We don't want it at the  top of the tower.  There is no opening below that we could snake  the  cable through.  In the past, we have either drilled a small hole, or found space through the door opening.  Unfortanately the city is not ok with us drilling a hole, so we have no choice but to run it alongside our base station cables.

I think I understand now. Sounds like the tower part is fully enclosed? Most of the water towers we deal with have an exposed lattice structure with a tank on top.