Is this a new unit 2019 or 2020? With the 16" wheel upgrade you have to look carefully to be sure the suspension (spring shackles at front and rear) bolts are located in the bottom hole of the 2-hole brackets. This is crucial for wheel well/tire clearance, but also raises the trailer slightly to increase bed clearance on your tow vehicle. To give you accurate measurement guidelines, it would also depend on the specific pin-box you have on that unit.
It also depends on what truck you tow with, some models have higher bed-rail heights than others. You will need to pay attention to the bed-rail clearance. I have a 2020 HT 30.5 CKTS and tow with a 2019 F-250. I had to move the suspension to the lower holes to raise the trailer so it rides level and has enough bed-rail clearance. The pin-box itself is adjustable, so you will need to know what setting it has.
On my HT, the standard Lippert pin-box was about 11" lower than the underside of the overhang. If you want at least 5" of bedrail clearance, that means you want your hitch plate set at about 6" lower than your bed-rails.
According to Jayco's spec for the HT with 16" wheels the pin-box height is 50 3/4" but I did not find this to be accurate.
I would highly recommend you try to get the specific measurements of the unit you are purchasing.
2020 Eagle HT 30.5 CKTS (16" wheels, spring shackles set on lower hole of frame, standard kingpin, B&W Companion slider)
2019 F250 SRW SuperCab 4X4 SB 6.2 (10,000# GVW) 3.73 Axle 18" wheels