We have here in christchurch a DR2X (VHF) on a mountain (No Internet) in north canterbury which is 48km away from my qth.
I have at my QTH a FTM-100 connected to a HRI-200 which RX + TX on the repeater frequency (low power TX-5w).
I also have here at my QTH a high power simplex hotspot (Tait TM8110 connected to a MMDVM) this is also RX + TX (low power TX-5w) on the Repeater frequency and the MMDVM is conected to the YSF59115 NZ-Canterbury-NZ Reflector.
All of this works Perfectly well but I found I have to have Remotegateway=1 set in the Fusion connector setting in mmdvmhost.for the audio to work in both directions properly.
I prefer using a seperate radio as a hotspot radio because I can set the TX and RX frequency seperately to what I want and the unit can be many Km's away, where as on a hat hotspot in simplex mode it only has setting for 1 frequency so a Duplex hat as Robin is using will let you set the TX and Rx frequency and it has to be next to the DR2X Repeater and internet needs to be available also.
I hope this has been of some Help to you.