You have a very difficult situation and there is not an easy answer.  What part of your body is the GVHD affecting?  I ask because if it involves the skin (and it often does), it is affecting the biggest barrier for you from infection.  If the GVHD is sparing the skin, then port placement may be an option.    A port would require less overall maintenance but would still be at risk for infection if you become neutropenic.  If the GVHD is affecting the skin, a port still could potentially be placed as they are surgically inserted below the middle of either clavicle (on the right or the left).  Keep in mind anything foreign in ones body may become infected. 

A port can be used for IV medications  such as chemotherapy, antibiotics and can also be used for CT contrast.  It takes a physician order to obtain lab draws from the port, but if you have become an impossible stick, then this is also an option. 

Before a port-a-cath can be placed, the surgeon does require your abosolute neutrophil count to be greater than 1.0, platelets greater than 50,000, INR less than 1.5 and a viable internal jugular or subclavian vein.  Hopefully this answers your questions.