My take on the numbers so far, is you have the necessary towing capacity in the Ford Ranger. Kudos to Ford for improving the towing capacity of the Ranger.
2020 Ford Ranger
We got sway bars, electronic braking
2020 Ford Ranger 7500# max towing (Please verify this is from driver’s door sticker!)
Payload on the Ranger is 1428lb (Please verify this is from driver’s door sticker!)
Dry weight or unloaded weight ???? (get from door sticker)
5680 CAT – ???? Dry = ???? actual payload
Max Pay 1428 – ???? act payload = ???? remaining cap
MGVW ???? (get from door sticker)
MGVW ???? – 5680 CAT = ???? (remaining capacity)
Max front axle weight ???? (get from door sticker)
MFAW ???? – 2840 from CAT = ???? remaining cap
Frnt Axl w/o TT 2840, w TT 2720 = 120 negative from CAT scale
Decrease this number if necessary by adjusting WDH. See WDH instructions.)
M
ax rear axle weight ???? (get from door sticker)
MRAW ???? – 2960 CAT = ???? remaining capacity
Drv Axl with TT 2960 - w/o TT 2200 - = 760 positive from CAT scale
MCGVW ???? (get from door sticker)
MCGVW ???? - 10600 from CAT scale = ????
factory rear
receiver hitch (sticker says max 750lb tongue, 7500 tow).
Tow V with TT 5680 – Tow V w/o TT 5040, = 640 positive from CAT scale
Tongue weight is 640 from CAT, (640/750) x 100% = 85% of hitch capacity
2021 Keystone Bullet 243BHS.
MGVW 6500 from sticker on TT
TT Axles 4920 from CAT scale + 640 tongue weight = 5560 GVW
TT MGVW 6500 sticker – 5560 CAT = 940 remaining (86% of capacity)
GAW 3500 each
.. 3500 x 2 = 7500 GAW combined
This number may need to be decreased a little because capacity may need to be de-rated when combined.
7500 sticker - 4920 from CAT = 2580 remaining
Cargo Capacity 1230 from TT tire sticker
Dry wt 5100#, 29ft. (This wt you provided in post above appears to be wrong)
Dry wt 5230 from TT weight sticker
5560 CAT – 5230 sticker = 330 cargo weight
330 / 1230 x 100 = 27%
All calculations I can make say your requirements have been met. However, you should get the Ranger’s driver’s door sticker values and finish the calculations above. See “????” above. So far I see no reason you cannot safely tow your new TT.
You may wish to have a more powerful or heavy duty tow vehicle for personal preference reasons. That is a different issue.
“drive home from the dealer seemed OK.”
“all my people, and got weighed. Looks like my tongue wt is 640. Trailer weight comes in at 5,560. I'm wondering if I need air suspension - with 240lbs more on the drive axle? “
Air bags are not the best device for a travel trailer rig. They may be useful for utility trailers that carry widely different loads from time to time. Bags will not change tow vehicle capacity. They only level the tow vehicle. WDH is a better tool. Adjust it if necessary. It will shift weight from rear axle to front axle for better stability.
I wish you good luck and happy trails ahead!