First is to check your tire pressures. Overinflation or underinflation can cause the wandering you're experiencing. Weigh all four corners or at least both axles and set your tire pressures according to the tire maker's inflation charts. DO NOT LET ANYONE TELL YOU DIFFERENT. Set your tires according to the weight charts plus maybe 5 psi fudge factor.
That might fix you right up.
It's easy enough to get the steering wheel straight when the wheels are aligned properly. I use Wingfoot/Goodyear truck tire/wheel etc shop; it's very important to ask them to carefully check all steering and suspension components.
I have a Safe-T-Plus. The MH steers like on rails which is a great for 23 years old. Louisiana busted loose my Safe-T-Plus and I was all over the road. Really bad. So when we could check we found that the bolts holding it to the mounting bracket were broken and loose; we replaced the bolts and she was on rails again.
My Safe-T-Plus clamps to the steering gear; it's not a tie rod but I don't know what to call it. It can take several adjustment cycles to get it adjusted to your center. Note that "center" might pull you to the left on a perfectly flat surface but would be just right on a crowned road.
Just keep at it and don't give up.