I'd continue working out your dose with the Caverject before adding other variables.
I'd also consider experimenting with novelty/sex shop cock rings as they give many injection users a nice boost. I won't expound further on that topic at the moment as I have numerous times in the past.
I believe with most doctors the answer to the question is still a firm "NO" as to mixing pills and injections.
I do mix pills and injections without issue but my situation may not resemble yours at all. I'm a radical prostatectomy survivor with nerve damage. So my reactions to mixing the 2 may be very different from yours.
The following is copied from a recent thread and may be of interest to you if you haven't already seen it:
When I got a new Uro and I mentioned that I was using both injections and Viagra he looked at me quizzically and asked me why. I told him that using the Viagra allows me to use a less injection mix. He just said "OK" and that was the end of the topic. It is my understanding that more doctors are recommending the combination but I can't document that and I'm not a medical professional of any kind. Ask your doctor and then use your best judgement. But if you decide to use the combination you should experiment with a greatly reduced dose of your injection mix before increasing to your normal dose so as to avoid the risk of priapism.
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Some publications on the topic that I could find. The jury doesn't seem to have made a clear final decision. Most are just abstracts. The last link may be the best:
Combined intracavernous vasoactive drugs and sildenafil citrate in treatment of severe erectile dysfunction not responding to on-demand monotherapy Ahmed M. Al-Adl, Osama Abdel-Wahab, Tarek El-Karamany & Ashraf A. Aal.
Please note this first one is a PDF.
https://www.tandfonline.com/doi/pdf/10.1016/j.aju.2011.06.008Why a combined intracavernosal injection with trimix and oral sildenafil is reliable therapy in the ultrasonographic evaluation of erectile dysfunction
Jong Kwan Park 1, Jung Sun Park, Sang Bong Jeon, Wan Shou Cui, Sung Zoo Kim, Kyung Koo Kang, Sung Won Lee
https://pubmed.ncbi.nlm.nih.gov/18476965/TREATMENT OF INTRACORPOREAL INJECTION NONRESPONSE WITH SILDENAFIL ALONE OR IN COMBINATION WITH TRIPLE AGENT INTRACORPOREAL INJECTION THERAPY
Author links open overlay panelCHRIS G. McMAHON, RAMIN SAMALI, HELEN JOHNSON
https://www.sciencedirect.com/science/article/abs/pii/S0022534705680858Early combination therapy: intracavernosal injections and sildenafil following radical prostatectomy increases sexual activity and the return of natural erections
K Nandipati, R Raina, A Agarwal & C D Zippe
https://www.nature.com/articles/3901448Combination therapy for erectile dysfunction: An update review
Rohit R Dhir, Haocheng Lin, Steven E Canfield, Run Wang
https://www.researchgate.net/publication/50596730_Combination_therapy_for_erectile_dysfunction_An_update_review