Thanks for reaching out! 
You will find an overview of the available config parameters for routing profiles at ors.engine.profiles.<PROFILE-NAME>.build | openrouteservice backend documentation.
To use the maxweight/-width/-height limits you might want to use the hgv profile. It’s also able to route over ways with OSM access=forestry once you specify options.vehicle_type=forestry in your query.
To enable routing over barrier=sump_buster you will need to edit the JAVA source files, as this is not something which can be done at the configuration level. As a starting point for your experiments you could take the hgv vehicle profile.
Last but not least, for modifying the default speed values, please have a look at:
Cheers,
Andrzej