I can vouch for good bass fishing in Little Hay in August.  And you can have the lake to yourself on the lone campsite.  Casting from the rocky point on the campsite can yield results too.  One potential drawback to camping on Little Hay... possible logging truck noise..  Uggh!

We tried, but failed, to find the 18a put-in this past August.  The weeds and tall grasses in the clearing were dense and waist high.  There were some ATV tracks that I walked trying to find the put-in, but I definitely wasn't going to drive our Toyota van into that area.  And, I never did see a clearing at the lake.  There is a moderate embankment with trees and bushes along the shoreline.  I couldn't see an easy way down to the lake.  Maybe it will be easier in the spring.

Also, we tried paddling the Aylen River from the 980 M portage south to the first swift.  We never made it.  It was too shallow.  But this was August.

It's time for the perennial comment on this type of thread...... 
Beginning of May, no bugs!  End of May, lots of bugs!!!

I'd recommend staying on Erables as well.  It's nice campsites are more spread out than on Maple.

I wouldn't call the Dickson-Bonfield portage 'tough'.  As Jd says, it's long, but it doesnt' have any difficult sections.  If you have lightweight gear, and minimal food, it's a doable single carry.  With a 5 minute rest every 20 mins or so, it will take about 1 hr and 45 mins.

We canoed into Provoking two years ago in October.  We parked at the East Beach of LOTR as the Park couldn't confirm that the gate at Two Rivers campground wouldn't be locked up for the season while we were in the interior!
The 900m portage, uphill on the way in, is very defined, but as previously noted, slippery when wet!
The campsites we aimed for were on the north shore of the lake, just west of the portage.  As you exit the small bay and enter the main body of the lake, turn right.  There are some large, hemlock forested sites available along the shore.
Theses sites worked well for the shoulder season camping, but I wouldn't recommend them in the summer months.

 

I've stayed on that site and I really like it.  A cosy campsite on a secluded lake.  BUT, there's only room (and level ground) for one tent without getting very creative.

Ralph Bice Lake and Rain Lake access points (#3 & #4) can be really crowded in the summer too!
So I would say use HWY 60 and do the Pen Lake trip. 
OR, drive a bit farther... to Shall Lake access, and spend two nights on Booth Lake, or Shirley Lake.
Less crowded still, and both lakes are beautiful with many nice campsites. (although you may hear logging trucks while on Shirley Lake).

Ditto.. vanslyke.   By far the best one for summer tripping is at the east end of the lake.