I have created a build that runs similarly to how you describe and is fairly conventional.
https://underrail.info/build/?HgUFCwkHAwbCoAAAAMKgwqBQRTYAAGppEjJpAAAAAAAASzliwrAZwpYkK0fCjygxwpAfDsKxwqXCpuKgigXis6wF4rewBd-_It originally used psi, but psi was easily removed and the build should still function just fine without it. I've left
plenty of skill points spare, to distribute into throwing as you see fit.
You could drop a point of Int and put it into Dex for the sake of getting grenadier without much of a problem, too.
The main feature of the build is low Perception, which would be a handicap without ignoring enemy evasion via Leading Shot and boosting damage output via Survival Instincts.
I know that some people can find it to be a pain to use Survival Instincts, but I find it makes the build quite versatile as you can choose to take a hit to your damage output in exchange for keeping your health bar full.
You'll get a fair deal of survivability out of 9 CON in Normal difficulty.
You mentioned going with a crit build, so if you follow this build, you can easily get over 80% crit chance with infused rathound armour, seeker goggles and focus stim.
As for getting stuck, the solution is to hard save often and avoid the few areas of the game that lock you out of being able to leave whenever you want until you are confident that you can clear them.
Off the top of my head, I can think of the JKK questline, the Praetorian questline, Zaman's lair, the Gray Army base and the Darkdwellers lair, there may be others.
If you're up for a challenge, I posted another shotgun build that has maxed out throwing skill with 18 Dex, making it very deadly with grenades. The build is powerful but also unconventional and is a bit slow to get going, especially without a degree of meta game knowledge. Still, I'll link it and if you're interested (I included a demo video), I am happy to discuss it.
https://stygiansoftware.com/forums/index.php?topic=8933.0