Yep. First to do is to separate completely mixed factors now.
CPU affinity behavior, multiple tasks per GPU behavior, multiple GPU per se behavior.

So, affinity locked as default, 1 task per GPU as default, await at least 10 tasks completions ON EACH of 4 GPUs before touch anything again.

BOINC say the VGA cards support OpenCL v2.0.

-no_cpu_lock as default override
How it can be default if you provide option to override default settings???
Default means no options supplied.

From stderr:

Name: Fiji
Vendor: Advanced Micro Devices, Inc.
Driver version: 1800.8 (VM)
Version: OpenCL 1.2 AMD-APP (1800.8)

That can be issue...

Task postponed: Triplet data corruption, retry from checkpoint.

So you need to check if AMD own OpenCL samples work well.

Leave app running in default regime w/o any additional settings.
Will it produce valid results in number being launched on all your GPUs?
Only when valid execution for all 4 GPUs with default settings will be proven firmly worth to try to speedup/improve things.

Also, any task result I looked into has many restarts. Try to be patient a little and not fiddle with settings. Allow few tasks to complete on their own, w/o restarts and re-sheduling between GPUs. Then provide links to their results on web page.

Make sure your config supported by AMD OpenCL runtime.
Test few AMD OpenCL samples from their SDK. If some fail then interaction with AMD support required.

Hi,
Your results show affinity mask 1. That limits the number of CPUs to 1.

The question is about running at "full bore", which I take as only using the laptop's own thermal management.
That really is a bit of string - if you are fortunate and the room is very cool, and the laptop has very good intrinsic cooling and thermal management it will last a lot longer than one that is in a very hot room and has very poor intrinsic cooling and thermal management.
Of course you can improve vastly the situation by using a PROPER external cooling pad - one which actually cools the incoming air to below ambient, or a utility like TThrotle.