Tonneau Cover with Cab Extension to Fit a 2020 GMC Sierra 3500 with BAKFlip MX4 Cover
Updated 10/30/2025 | Published 02/01/2025
Question:
I have a 2020 gmc sierra 3500 with a bakflip mx4 cover on it. I like to put a ladder rack, that goes over cab on it with leaving cover. Is this possible? And ease to remove because I tow a 5th wheel sometimes. I carry long trim pieces that are flimsy and long.
asked by: Alan S
(click to enlarge)
Helpful Expert Reply:
Hey Alan, thanks for reaching out!
We do have one ladder rack that will work with your 2020 GMC Sierra 3500 setup with the Thule TracRac SR Sliding Truck Bed Ladder Rack w/ Cantilever # TH44RE. This is able to easily be removed from the base rails like what you're needing, but there are a few things to keep note of with this setup.
It will fit with your BAKFlip MX4 cover, but the rubber seals on the sides of your cover panels will rub against the black base rails so it's possible that over time the seals will wear down - so this fits with your cover but it will be a VERY snug fit. The other thing to note is that the base rails will raise the height of your truck side rails so you'll also need to double check that your 5th wheel won't make contact with the rails when you turn. These rails will increase the heght of your bed sides by about 1-1/2" just so you have something to go off of.
If you're willing to swap out your tonneau cover to something else, there is the BAK Revolver cover (you'll need to get it from BAK) that fits with the TracRac SR perfectly so it's another alternative that will work and still offer protection for cargo you want to put in your truck bed.
Do you have some tie downs already?
Product Page this Question was Asked From
Thule TracRac SR Sliding Truck Bed Ladder Rack w/ Cantilever - 1,250 lbs
- Ladder Racks
- Truck Bed
- Sliding Rack
- Work
- Not Tonneau Compatible
- Over-Cab Height
- 1200 lbs
- Over the Cab
- No-Drill Application
- Thule
more information >
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Jon G.
10/30/2025
Hey Alan, how did the TracRac SR ladder rack work out with your Sierra and BAKFlip cover? Did the snug fit or rail height cause any issues when towing your 5th wheel? Your update could make it easier for others with the same setup.