[TowerTalk] Does this make any sense?.....

[Peter Sils]

After almost 40 years I am finally going to put up a tower! I already have the building permit for a Universal 15-40 aluminum tower and was able to buy a new Force 12 C-3 at a good price.
 
Now my questions are: 
 
Does it make sense to buy a Cushcraft D-40 (40 meter rotatable dipole) and place it above the C-3? I would be able to separate them by approx 10' and the D-40 would be at approx 50'. I know this is quite low but beggars..... (My primary interest on 40M would be DX).
 
If it makes sense, do I mount the D-40 parallel to the boom or elements of the C-3 to minimize interaction?
 
DX Engineering has vinyl end caps for boom and elements but am I just trapping in moisture? Would you use them or just leave the ends of the boom and elements open?
  
Any help, insight, thoughts and direction would be GREATLY appreciated!
 
TNX in advance!!
 
73 Peter
KD0AA