A cool combination that can work very well together is the MX4 with the Elevate TS rails that add the option of the t-slot capability
On this I do want to point out is that Retrax covers do take up about 12" of bed space. The only reason I would suggest the MX4 in your specific situation is you are already concerned about losing bed space with the Peragon cover, the MX4 gives you the option of 2/3 bed access, full bed access, or the option to easily remove if desired.
Both are great options and as you know we offer some great pricing
One thing I do want to clear up as I have seen a few people say it on this thread and on others. When new generations come out, doesn't matter it is Ford, Ram, Chevy, Toyota ect. there are changes made to the beds. While yes the length may stay the same but different aspects of the bed change which causes covers to not fit properly from one generation to the next. While this is an inconvenience on having to buy a new cover we try to lessen that impact by offering forum special pricing. I'm not adding this as a sales tactic to get you to come to buy one from me immediately or at all, the purpose of this is to more to inform you all that have one of these covers and it isn't installed properly (swapped from one generation to the next), it can become a liability to you and not keep the bed secured properly from the elements or would-be thieves.