Congratulations! The trapezoid pickup Fenders are the best! A Fender Dual Pro with E13th and C6th is just about the best straight steel setup one could have in my opinion!
My advice would be to look out for two common problems associated with these.
First, the tuners on these (called lollipops) are attached to the tuning pans, if it a tuner becomes stripped it can be a hassle to replace.
Secondly, the pickup has a plastic surrounding around the strings that can shrink and cause the strings to buzz. If you ever hear some buzzing this may be the culprit. I am not sure at all, but it seems possible that Fender fixed this issue in the last years of the Trapezoid models’ production, so you may not encounter this.
————
As far as random non-technical advice, I think E13th variations are worth exploring! Which of the many different E13ths are you currently using?
Two of the best are the Leon McAullife and the Vance Terry E13ths (all tunings hi-to-lo):
E C# B G# F# D B E (Leon E13th)
E C# B G# F# D B G# (Vance E13th)
————
Kayton Roberts had (and Chris Scruggs has) these two tunings together on their Dual Pros:
E C A G E C# A A (C6/A7th)
F D A F G Eb C F (F13th)
(Pitched in E that F13th would be:
E C# G# E F# D B E)
Here, instead of being pitched in E, the second 13th neck is tuned up to F because the bar positions purportedly line up with the C6th neck when neck hopping...
Strings 4 and 5 are actually out of order pitch-wise, presumably to allow for the same slants as the old C#minor and F#9th family of 6 string tunings developed in the mid-to-late 30s:
E C# G# E D B (Hawaiian E13th aka C#min7th, used by Andy Iona)
E C# G# E A# F# (F#9th, used by Dick McIntire)
The Kayton Roberts 13th is also similar to the Noel Boggs E13th in that there is a lower B string instead of a high B string:
E C# G# F# D B G# E (Boggs E13th)
————
I currently use my own crazy 13th tuning on my furthest neck of my Custom, though tuned up to F#, so as to retain the E on top configuration:
E D# C# A# G# F# E A# (My F#13th)
D C# B G# F# E D G# (pitched in E)
I think having the b7th interval on top imparts a unique sound, and all the other intervals of the 13th chord (except the lowest A# string) are as close to each other as possible.
Along with some insane slants, it allows for some pretty harp-like cascading, arpeggigiated 9th chords similar to those found in Jerry Byrd’s C Diatonic tuning.
Everyone is crazy for the blonde Fenders, but I think the brunettes like ours' is where it’s at!
Keep us posted!