Just had a quick look. I started DOSBOX (0.74), mounted hard and CD drive, ran install from the CD drive, chose FULL and Soundblaster 16, which installed Thunderscape without a problem. Then I started Thunderscape by entering THUNDER at the DOS prompt and entered a new game by simply accepting the preconfigured party. I found the loading times relatively long, but still acceptable. Everything looked as it should, sound was there.
So far so good.
Then I went into the fight with the bees and noticed that the fighting animations slowed down the game noticeably, including stuttering sound. Increasing cycles (SHIFT+F12) helped a bit. But the rest of the game ran smooth, including sound. Then I noticed that the options let you turn off those animations, which solved "most of" the problem. You still see the bees moving, and this seems to cause little lags - nothing serious in my mind.
That's all for now. To sum it up: If you can accept fights without seeing swords (and probably magic effects), then switch the animations off, play with the cycles a bit (if necessary), and you should be fine.
There are other ways to tune DOSBox by playing with the graphics options in the conf file - I may give it a try later or in a few days when I have more time.
What you said about the "2 solutions" in your last post is just a way to make starting Thunderscape a little easier. You create a game-specific conf file (use the standard conf file, enter your starting commands in the autoconfig section at the end of the file, tweak other conf file options if desired and save it under a different name and/or in a different place), create a DOSBox shortcut on the desktop (or somewhere else) and call the modified conf file from this shortcut using the -conf option (right click properties and modify the command in the target line in the way you described it in your post). This should do it.
Good luck!