1E AD&D - Gaming the System

As we approach the end of Pharaoh, something has become evident. The Desert of Desolation series is a little light on loot and magic items, which does hamper the rate at which experience points are gained.  Now, the PCs are all levels 5-7, which is the sweet spot for AD&D play, so these levels should be enjoyed.  But, if we are to complete the series it might be a bit of a struggle:

Pharaoh - for 6-8 characters of levels 5-7 - perfect
Oasis of the White Palm - for 6-8 characters of levels 6-8 - the party are towards the lower end, but should be ok
Lost Tomb of Martek - for 6-8 characters of levels 7-9 - this is where a problem could arise.

The series expects each member of the party to gain 1 level per adventure, but does not give enough loot for this to happen.

So what to do?

Here the 1E rule of xp for selling magic items comes in.

A Ring of Protection +1 gives 2000xp if kept and used, it is worth up to 10,000gp if sold.  And xp is awarded at 1xp per 1gp value.  So selling it accrues 10,000xp.  As the 2000 has already been awarded, the party would get an extra 8000 if it was to be sold.

Quite a few cursed items have a significant sale value too, as some have uses for 'certain types' of people.

It's not a rule I like, as it feels a bit too 'gamey', but it's there specifically for times like this.

I just need to add a few rich (but well guarded!) traders in the Oasis.