You should be OK
The Meanwell EPP 400 is capable of 400 watts (on paper). From experience with cheap Chinese electronic modules, I usually de rate them 50%; however Meanwell is well established as a reliable supplier and assuming you have a genuine Meanwell power supply you can probably get 75% of the 400 watts from in continuously with peaks of the full 400 watts for a few minutes at a time. Cooling is the big issue with pushing the limits of either the power source or the DPS.
The DPS 5020 is rated for 1000 watts and I definitely would de rate it 50% for long term loads but even so you are not pushing it with the EPP 400. In any case, I would not leave the setup unattended and keep an eye out for hot spots.