First thing, I like is that you will have full control of elevator due to the exhaust flow close to the surfaces. Don't know if the 8 degrees is right. I would try at 3 to 4 degrees. Way to determine that is when you have it flying trimmed at say 2/3 flying level, punch the throttle and if climbs/ nose down, you need to change angle of exhaust. Also, check if it skews off left or right. My slow flyer(EDF) ended up three degrees up and 1 degree right without an exhaust tube. Check out my SR-71 for comments on inlet ducts and exhaust ducts.
I would not do a mix of throttle to elevator.
Hold plane vertical, add throttle until it wants to hover(also an general indicator of 2 much or 2 little thrust angle side or up/down). A safe bet it should fly with 1/2 to 2/3 throttle.
Do an overhand throw and release level.
Do a short flight (1 to 2 min) for you will gobble up watts and you will have spare if you need to do a go around to land. Average flight is 3-4 min.
For the first landing, always
have some power on until you are about a foot of the ground and then flare. EDF's need to spool up and if you are flaring and too high and decide to go around, !!!!!!!!!!! I use a modified throttle curve to offset spooling up.
Watch what happens for landing and watch the chucking at second time. Happy because it took me many moons to solve for no vertical stabs and no rudder where I used only 2 servo and a thrust vectoring unit to apply necessary yaw.