First post so go easy on me!

OK, so it's fairly common knowledge that the last tier of the Space grind is fairly harsh at 1 mill xp per box (4 in total). Not everyone is able to find an Ace who is willing to run them up to Ord Mantell to gangrape the Tier 6 pirates which consta-spawn at certain points, so this might make it a little easier for you.

One of the best sources of xp in space at this level is Kessel and some of the best xp in Kessel comes from gunboats. Not everyone likes going up against them due to the number of weapon points. But it is possible to take them down solo in ~1 minute (with practice), taking minimal to zero damage...even with only a small amount of skill!

Tactics:

Imperial YE-4 Gunship
If you approach the ship 'side-on' you will notice that one of the tail fins is shorter than the other; This is the underside...which happens to be completely unprotected. Guns 0 and 1 are forward facing, gun 2 is rear facing and the rest are located at each corner on the upper side of the ship. If you carry out strafing runs on it, approaching it 90 degrees on, you will be able to fire without any risk to yourself. I would also suggest targetting the engines first, as this will stop it from jumping out on you mid-fight.
Some people will recommend that you approach from the stern and take out Weapon 2. I'd suggest against this as a well placed shot from these gunships will take out a fair amount of your shields (Disclaimer: depending on the skills of your shipwright!) and, if you're not quick enough to avoid the second volley you'll start taking serious damage.

Rebel Gunboat
This follows a similar tactic. Approach the gunboat from the underside, which is more easily identifiable than the Imp version due to the configuration of its wings. Once in position, roll so that your target is below you. Ideally you want to be approximately 400-500m away from the ship to allow for your approaches. Now, match your speed to that of the gunboat then increase it slightly. What you are attempting to do is fly a kind of 'roller coaster' path where everytime you are on your 'descent' you are shooting at the underside and your 'ascent' is designed to set up your next attack run. The gunboats weapons only fire laterally and upwards, so the underside is defenceless. Again, target the engines first to stop it from hypering out on you.

Notes:
One of the tricks to this method is picking your target correctly. In my experience, the majority of the Kessel gunships/boats will fly in a straight line between two waypoints then hyper out, which makes this method easy to accomplish. The only exceptions to this rule are the advance 'scouting party' craft which appear ahead of the 'vettes. These will change vector fairly regularly and will jink like crazy when you attack them, making it difficult to maintain your position under the vessels. If you come across these...save your ship and booster the f*&% out of there!

Result:
~33k space combat xp
~320 ground combat xp
~22 GCW pts

On a side note, apart from the 'vettes themselves, one of the other highest xp per kill targets in Kessel is the TIE Oppressor. This is more favourable to the Aggressor as it does not have the rear gun to take pot shots at you as you tail it. It also gives ~8k xp per kill.

These xp figures don't take into consideration Ent inspiration buffs to xp gain.

Hope this helps.