Take a look at this link....there's plenty there to digest. UAVJOE's post's are very similar to your set-up and he's had lots of success without reverting to any wooden platform on the HK H4:
Your biggest hurdle will be weight/power ratios once you add the batteries, which may end up being a combination of 2-3s 2200mAh.......since the design is a rectangle rather than square, balance issues after loaded-up with equipment come into play as well.
Motor mounts on the stock design seem to have problems with vibration and stability.......if you intend to vid anytime soon......
Looks good leadpan....progressing quite well!