Being a first time driver of this thing myself, I too was alarmed at the drift in steering. Once I got a bit used to it I found myself starting to relax a bit... then I realized I was leaning over to the right going down flat lane highways.. and noticed it even more especially in left hand turns... and it played into the unit drift of the steering..
I had just loaded this thing with fuel (propane and Gas) and thought that might be an issue.. but the fuel tank is centerline so that ruled that out. The propane is too small for the kind of weight lean I was seeing.
I had also loaded personal belongings including about 2000 rounds of ammo of various calibers. So I decided to stop and shift any of that to the opposite side and see if that helped.
It did however I think the problem is not solved in my case. I am thinking that a shock and possible a leaf spring has gone bad on the one side. I have also noticed the front is very soft on bumps.. which tells me all the shocks may be bad and need to be replaced.
Shocks have a HUGE impact on steering of ANY vehicle but especially large ones that weigh as much as these do.. I would suggest having your shocks and springs checked..
I am having all mine replaced. I got very lucky buying this 1998 38' Fourwinds Windsport RV for only $5000. To date I had only put in about $1500 in repairs to start. With this work I will be up around $3000 added... still a heck of a deal regardless.