Here are some news, how you can preper your GPA for nearly all bands very easily.

Always I did use a GPA50 for my dxpeditions. This groundplane works on 10, 15, 20 and 80 mtrs. But what about WARC...

GPA50 consist of the rod and 3 radials. If you have  metallic balkony railings or an other bigger metallic corpus like roof gutter

you don't need these radials. You can work on the bands above like before. Last times I used a scaffolding to mount the antenna.

But put these radials now at the feeding point of your antenna rod. You will get following SWR:

The longest (ex-) radial (5,4 mtr) you still can optimize for 30 mtrs with better SWR. But it is good enough for IC706 giving full power.

If you like to work on 40 mtrs, so you must make the 5,4 mtrs wire longer. Tie a 4,0 mtrs long wire to the 5,4 mtrs and it will be ok for 40 mtrs.

But you can only work on 30 or on 40 mtr band. An additional 9,4 mtr wire make you ready for 40 mtrs but destroy 30 mtrs.

If you have no "matallic balcony" you must use any radials. But also in this situation the descripted "feedpoint wires" workes as above.

So you have got an 8 band sw groundplane for your next trip. But tell me where you go...

Still one hint: 

--- or did you know following...

Did you try once 6 mtrs??  In Germany there is not allowed to work in vertical polarization, but...  your GPA50 doesn't mind it. 

As TA4/DL7CM  f.i. I could work FR1AN.  SWR is 1:1.5 and antenna is running well.