小中大I think your target is too long for RACE. Although some kits say they have ability to amplify the long distance RACE, it is hard to test all the sequence. In this case, I think you can try to use the conventional RT-PCR and RACE.
3-4 kb is ok for the good kit when they use in RACE, 7 kb is not a good target. You need to find out the mid sequence of this gene, and amplify the mid-fragment with RT-PCR maybe 3-4 kb. Then you can design the new primers for the rest fragment.
At the same time, the denature time for the template is a key factor for long PCR. If the GC% in the target is more than 60%, just use 94 or 95 degree 5-10s.
For the RACE, I suggest you use the 65-72 degree for anealing temp.If the temp is too low, You can not get what you want.