Welcome to JOF
IMO I believe you will find that your Terrain isn't an ideal match for the SLX 7 174BH (has same weights you posted).
It's best to start your TT search with minimal guess work........,
Take your Terrain to a CAT scale and weigh it under loaded conditions (full fuel, passengers, and cargo). A CAT scale weigh-in is about $9 and takes 3 minutes....., just place your TV axles on the two platforms and push the button.
Subtract your CAT scale weight from your TV's GVWR of 4,850lbs......., the remaining weight is your actual "available" payload capacity. The available payload capacity is the weight you have for a TT's "loaded" tongue weight (?) and hitch weight (40lbs)
The 2019 SLX 7 174BH will have an actual "as-shipped" weight around 3,000lbs (yellow sticker on side of TT).
Hypothetical 'conservative' 174BH loaded weights: (3,000lbs UVW) + (50lbs Dealer-battery, etc.) + (350lbs cargo) + (no fluids
) = 3,400lbs
Recommended loaded tongue weight range @ 3,400lbs gross: 340lbs (10%) - 510lbs (15%) of gross. IMO for enhanced TV handling of the single axle 174BH one would want a loaded tongue weight closer to 13% minimum (442lbs @ 3,400lbs gross).
Just food for thought.
2016 GM 2500HD 6.0L/4.10
2018 Jay Flight 24RBS
2002 GM 2500HD 6.0L/4:10 (retired)
2005 Jayco Eagle 278FBS (retired)
1999 Jayco Eagle 246FB (retired)
Reese HP Dual Cam (integrated sway control)