You need to start with the basics of checking the wing for warps. Then check the fuselage for lengthwise bowing (bannanna shape). Then check for lateral wing balance. Finally ensure that the ailerons are both sitting identically when centered and do not jut above or below the main panels. A bad hinge line where the control surfaces are not "fair" to within better than 1/32 inch can generate a yaw producing drag even when the aileron is supposedly "centered" and also act like it is adding roll trim.

Only when you KNOW from testing with long straight edges that the fuselage and fin are all straight and centered can you mount the wing and check the wing alignment to ensure it is sitting square to the center line and that the semi spans on each side are identical to within 1/8 inch. Any diagonal misseating should be held to within 1/16 inch as measured from the wing tips to the fin centerline. These diagonals can only be checked once the wing is confirmed to be seated so the span on each side is identical to within about 1/32 inch. Otherwise set up measurement points that are that accurate to check the diagonals to the fin. The wing only needs to be skewed a couple of degrees to genenerate that much of a trim issue.

5 degrees of right thrust does seem like a lot. You could very likely reduce that to around 2 to 3 and that much would do all that is required. I'd suggest start with setting it to 2 degrees and check for warps and wing alignment as mentioned above. Wing warps of as little as 1 degree difference from panel to panel can produce what you're getting. Any warping much be dealt with unless it's an identical amount and direction on both panels such as when adding in washout to aid in avoiding tip stalls. The obvious message here is that both sides of the wing much be identical in every way. Even some differences in mis-shaping of the airfoil from side to side could cause this issue if the mis-shaping is pronounced enough.

Take nothing for granted, Check everything looking for anything that is non symetrical.