I mounted an IRX4 Lite 4 in 1 Multiprotocol module inside my ELRS Jumper T20 V2.

While the original T20 seems to have plenty of space to mount a module internally (they even sold a kit to mount crossfire internally), the V2 is very cramped inside. This position was the only one i could find that didnt involve cutting.

I have stock gimbals (not RDC90, or AG01), so not sure if this will fit with other gimbals... Its basically sitting sandwiched between the gimbals and the rear shell.

There are two parts to this - The two brackets that hold the multiprotocol in place (use PLA, PLA+, PETG or something else that is sturdy - it is more to position the module rather than be completely rock solid), and a little rotatable T antenna holder (TPU) that goes where one of the rubber stoppers went in the shell.

You will need:
IrangeX IRX4 Lite (https://usa.banggood.com/IRangeX-IRX4-LITE-CC2500-NRF24L01+-A7105-CYRF6936-4-IN-1-Multiprotocol-TX-Module-for-Frsky-X-lite-p-1346927.html) this was only $30 when i ordered
4x M2 screws at about 4mm long (I cut some nylon screws down, or you could use motor screws)
Molex A1254 6 pin plug with wires (https://www.aliexpress.com/item/4000818221650.html)
JST 1.25mm 5 pin plug with wires (https://www.aliexpress.com/item/1005005373314119.html)
ExpressLRS T-antenna with 80-90mm lead (https://www.aliexpress.com/item/1005007481088213.html)
Some Kapton Tape for insulation

Remove the external module adapter board that is on the rear shell. Reuse the screws to mount the brackets in place as per the pic.

Remove the IRX4 Lite from the shell, remove the antenna and the plug that connects it to the pin header on the shell. Mount it as per the pic.

Solder the pins together with about 80mm length of wire (you can see from the pic and measure yourself if you want). Note the wire ordering, and that vcc and gnd have two wires each on the IRX4 side, which connect to one wire each on the JST plug side. Also one of the JST plug pins isnt used - i removed it from the plug to save confusion

It should fit together with no pressure. If not, open slightly and see where it is hitting - dont try to force it together.