Sealing around a vinyl siding mounting block

I had to remove a wooden mounting block on my vinyl sided house (it was there when I moved in), of course the wood rotted. I purchased a jumbo mounting block to fill in where the old wood block was, and old J-Channel. I used a siding removal tool, installed the new mounting block like the one shown. I'm just not satisfied with the bottom corner in the red-circle, to keep water out. Now I installed this on an existing house, and have 2 light fixtures to do yet. I don't know how good the house-wrap is underneath, so I don't want any water seeping in over time and doing damage. I have searched the web, and found nothing. I've seen "Big Stretch" caulk, to seal the box to the siding, and then put the trim ring over it. Any other ideas?
q sealing around a vinyl siding mounting block, curb appeal
  15 answers
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