Remember that your mpp will be around 75-80% of Voc. You could find a smaller panel with the same Icc (I closed circuit) to put in series so you get a higher Voc. Also note that the smaller (and cheaper) 100/20 charger might be sufficient for your limited pv input. It can handle 1kw pv on a 48v system. Worth checking out.
I have experimented with this for my systems. You can use an Orion-Tr 48/48 converter power matched to the panel they go up to 380w to boost the voltage from the panel and output that into a 100/20 with a 60V output setting. Or you can setup a small 12v or 24v battery and charge from the solar then boost with an Orion-Tr 12/48 or 24/48 into a 100/20 MPPT. You can adjust the charge current in the 100/20, it will be quite low only a few amps 5-7 max with this setup. I am going to assume you have a 400w panel you only have voltages. The second option will work best but needs lots of parts.
I want to apply a solar of 500Wp on roof of campervan.
There are also another options.
That is a high-voltage PV panel that is only available for business, but not for homeowners. Like Sunpower Maxeon with Voc=70V. I need to find out.
Buy a second panel and cover it partly under the first panel. Here 60% of the area will not get any sun energy (bypass diodes activated) and the remaining will have a certain voltage e.g. 15V. Total voltage will be > 53V.
Am I understanding wrongly for option 2?
The mppt is designed to draw the maximum amount of power available from a solar panel given the varying amount of sun (power) that is available.
Under low light (or varying light) the boost controller will not be able to give a steady voltage output.
Given you can fit 500w of panels on your roof, choose a 500w panel with a high enough Vmp to suit the mppt @ battery voltage.
Or 2 x 250w panels.
Or 3 x 170w panels.
Or 4 x 125w panels.